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Page last modified: 09/01/10 Fuel/ExhaustNote: Email addresses and links listed in this Q&A section may no longer be valid!
DATE: March 19, 2000 [This article should be required reading for those with carb problems.] I live in England, and when It is warm I had no problems what so ever with my GS650 Katana, but when it started to get cold, starting it seemed the same story. It would start, run on idle for about 1 minute then stop. Would it start then ? no chance, only after leaving it for about 30 minutes would it start, and then it would give no problems. I did all the usual checks and for some reason fuel was not getting into the cylinders. I had checked fuel from the tank and carbs which seemed OK...except that I hadn't looked close enough. RIDER: Graham Steers REPLY: Graham Steers I hope this may be of some help in contributing to your
excellent site. The inside of my tank was very rusty. This past winter I cleaned it (got almost two cups of rust scale out), acid etched it, and KREEMED it. While I had the tank apart, I noticed that the fuel gauge float assembly was also quite rusty. This may be your source of rust since the inside of your tank looks clean. I put a new paper filter on (the old one had about 1/2 cc rust caught in it) and so far it looks very clean. I hope I have my tank rust problem licked. Good luck with yours!! DATE: March 19, 2000 I recently acquired a GS550, that hasn't been run in a decade or more, but was garaged the whole time. When I get it running, it will be my first bike! S/N GS550E-723778 mfg 7/80. The S/N says "E", the right body cover says GS550L. How can I tell which model? I bought the manual, but it assumes that lines are in the correct place to start... The lines to the gas tank aren't connected. Two nipples on the gas tank tap, three T-nipples between the 4 carburetors. What hooks to what? The vacuum switch hose from the gas tank is also not connected. Where does it connect? There appears to be a nipple on the forward part of #2 carb (counting from left) that was jury-rigged plugged with a short piece of hose and a screw. Any hint on what line should go to this nipple? (Just guessing, the gas tank vacuum switch hose?) Great site, I just registered on the 550 list. Any help or hints would be very appreciated. Thanks very much, Curt RIDER: Curtis L. Engelbrecht REPLY: John G. Bloemer Counting from left to right facing the front of the bike the carbs are 1 through 4. The "T" fittings in between # 1 & #2, and again between #3 & #4, are carb bowl vent lines. These generally go up over the top of the carbs towards the rear. Some end up under the seat (1982 GS750tz), mine go up over the top of the air-box to a clamp on the right rear of the air-box. The "T" between #2 & #3 is the fuel supply hose. This attaches to the larger outboard nipple on the fuel petcock at the tank. the last fitting on the engine side of #2 carb is for the vacuum line that goes to the smaller inboard nipple on the fuel petcock. This vacuum line opens the automatic petcock when the engine is running. Good luck with your restoration!!! Be sure to check out all the Q&A sections of the GS Resources web site. There is lots of good stuff there!! DATE: March 19, 2000 I was talking to my local Suzuki dealer about putting a 4 to 1 system on my bike he said that there are probably not any for my bike. is this true? if anybody knows where i can get a system please contact me. thank you RIDER: bill lobuzzetta REPLY: Joe Amidon DATE: March 19, 2000 I need to reset the air mixture on my carbs using the upper screw (the one accessed from above). All my manuals say that these are factory set with special equipment, but why would they put a groove in it if it wasn't meant to be turned? The bike runs great, but the idle is rough. Carb sync and everything has been done. Does anyone have the specs on these settings? Thanks. RIDER: Eric Calbow REPLY: Frank Perreault DATE: February 20, 2000 What jet sizes should I start with for a set of Mikuni 29mm smoothbores? The carbs will be using individual K&N filters and the bike has a 4 in 1 pipe. RIDER: Dave Lambe REPLY: Chris Hunter Cope Racing has a webpage with recommended settings for 29mm
smoothbores: DATE: January 29, 2000 My 81 GS750E has 34,000 miles on it and has been cared for for the last 19 years by myself or my brother (who purchased the bike new). My problem is that fuel drips out of the #2 exhaust pipe when the bike is idling. It runs poor (I'm assuming on only 3 cylinders) til this fuel clears out and the #2 cylinder kicks in. Then it runs awesome. I took it to a repair shop and they rebuilt the carbs and the fuel petcock. The mechanic called me to pick up the bike and told me that the bike still leaked fuel and that it was just too old and had too many miles to fix properly. It's compression ranges from 105 to 120 PSI and I am offended by the mechanics comments. I love the bike and want it fixed...Can you help me? RIDER: Craig Kellett REPLY: Frank Perreault My suspicion is that there is a very small "pin" hole, or very small crack, in the diaphragm allowing raw fuel to be sucked into #2 cylinder. The hole (leak) is small enough to only noticeably affect lower engine speeds, and not large enough to flood the entire cylinder. If the leak becomes severe the #2 cylinder could fill with enough raw fuel to fill the compression space when the piston is at top-dead-center (TDC). THIS CAN CAUSE SEVERE ENGINE DAMAGE, AND LOSS OF CONTROL IF IT HAPPENS AT SPEED. What happens here is that liquids cannot be compressed like the normal fuel air mix. The #2 piston comes up and hits the liquid filled space and causes an engine wreck (bent connecting rod, blown out upper or lower connecting rod bearing, or if you are lucky only a blown head gasket or blown out sparkplug). I have a clear vacuum line on my GS850 (see fuel being sucked in), and I am in the process of adding a manual in-line (Briggs & Stratton) fuel shutoff valve down stream of the "automatic" petcock. My "automatic" petcock did not shut-off completely. I smelled gas in my garage and saw that gas wetted the bottom of the the air-box. I pulled the carbs, removed the plugs, propped the plug wires high up out of the way and cranked the engine. Fuel shot out #1 & #2 spark plug hole like a hose. This could have been a disaster had I cranked the engine normally and #3 or #4 cylinder fired (engine wreck mentioned above), or something in the starting motor linkage broke trying to compress the liquid fuel. Good luck!!! DATE: January 29, 1999 I bought my 550 for $40 from a guy who let it sit in a parking lot for about a year and a half. I took the carbs off and cleaned them out. I could then get the bike to run, but only if it was fully choked, and even then it ran almost at red line. I found a leak in one of the intake boots (between the carb and the engine.) I bought a new boot, but in the interim, I sealed the leak with some tape (pretty sketchy move, I know) and now I can only get my machine to fire if I spray the air filter with starter fluid and it only runs until the spray is burned off. I am pretty sure that I got all the jets, even the pilot jets, cleaned out. The spark plugs look pretty dark, but not as bad as if it was running rich or burning oil. I bought the bike as a project so I am reluctant to just drop it off at the mechanic's shop, at the same time, I am stumped. Any suggestions would be welcome. RIDER: Nick Johnson REPLY: Chris Hunter DATE: December 27, 1999 Great Site Guys... I have a 1981 GS750E that I recently moved from the west coast (5000 feet) to the east coast(250 Feet) and all of a sudden #3 and #4 have stopped firing yet I seem to have good spark but the plugs on #3 and #4 are black and wet and #1 and #2 are dry and light brown (good compression on all four). I've rebuilt the carbs twice and can't find any problems, I have fuel in the carbs and when I turn to prime fuel flows through them out the bottom of the bowls fine. I drilled out the caps on the air fuel adjustment screws and tried fiddling with them but made no progress. The bike is all stock w/112.5 main jets.. HELP.. RIDER: Bill Angleton REPLY: Chris Hunter DATE: December 27, 1999 This is 2 questions really, first, after standing for a few hours, there is fresh oil on the spark plugs. Could this be anything other than valve guides? The bike is a pig to start, and when it does, there is no smoke until about 3,000 revs. then it blows out a lot of blue/white smoke. Secondly, the bike has a non standard tap on the tank (not vacuum activated), and when left in the incorrect position i.e. "on", the carbs overflow, and quickly empty the tank. I can't tell if the fuel is coming from more than one carb, but I think it could be a stuck float or 2? Any suggestions would be appreciated. Cheers. RIDER: Tim Lovegrove REPLY: Rick Patrolia DATE: December 12, 1999 I want to lean on this great site for some help here. I have read many questions about carb problems and see much reference to adjusting "air-bleed" screws and such. I have the carbs that have diaphragms on top, I think they are referred to as "vacuum secondaries" or "CV's". They are the stock carbs and I need to know what size they are and what they should be referred to as , hence (BS32SS). Next, I am trying desperately to get this bike rideable and I have completely disassembled these carbs at least 5 times and soaked the bodies in lacquer thinner thinking something must be stopped up or something. My problem is this, the bike will idle just fine any where from 900 rpm's to about 1300 rpm's , which I consider to be a good range for the idle circuit , but when I get the rpm's up to about 2500 rpm's to 3000 rpm's , she starts breaking up and popping back thru the carbs. I can pull the choke on about half way and then I can get her up to about 5800 rpm's to 6500 rpm's and the crackling returns. To me it sounds like she is going lean at the lower rpm ranges with NO choke, and then again going lean at the higher rpm ranges WITH the choke. How well will these carbs perform without the air box installed (for shop running only), I have installed the ! air box and I get the same results. Also , because I have never ridden this bike, or even a bike like this one, how come my choke knob will NOT stay up ? It is very difficult to depress the clutch, mash the "start" button , and hold the choke "up" with only 2 hands. I had a problem with the choke cable being gummed up and I cleaned it and lubed it with my cable luber and now it will not stay up. It moves so easily, I guess I got her to slick. I was wondering if these bikes have some kind of method like "pull the choke up , then twist the knob, and this will lock in the CHOKE position" or something. I can't find any way to keep it up except with vise grips....The choke return spring is on the carbs located among the lever mechanism, no adjustment that I can find to reduce the tension. Also, the stock exhaust system was completely rusted so I purchased a MAC 4 into 1 pipe, could this be my problem ? Do I need larger jets ? if so , which ones ? I have found 3 jets in the carbs , 2 of them are in the main body of the carb in the float bowl area. The first jet would be the one that is directly in-line with the long needle coming from the vacuum diaphragm , this I suppose is the "main" jet. The second jet is located under a rubber stopper right beside the "main" jet. What is this jet called and is this the idle circuit jet? The third jet is located in the carb face where the air box connects to the carb body. What is this jet called I think mine has 780 stamped on it ? Is this jet part of the idle circuit ? O.K. back to the possibility of me having to re-jet these carbs because of the exhaust system, what sizes do I need ? I am pretty sure the jets that are in the carbs are factory spec. Also, I cannot find any screws to adjust anything on these carbs except the main butterfly positioning. Do I need to start drilling holes to find these adjustment screws ? I don't have a manual for this bike so therefore that is probably the reason for all my stupid questions , may be Santa will bring me one ! Thanks for the help ! and this is one awesome site ! I read thru it at least once a week ! Ron, RIDER: Ron Peterman REPLY: John G. Bloemer The carbs on the 1981 GS850GX are constant velocity (CV) Mikuni BS32SS. The 32 in the BS32SS is for 32 mm throat diameter. There ARE idle air screws on the top of each carb just in front (towards front of the bike) of the vacuum slide covers. They are under little aluminum caps with very small holes in them. These caps are a result our government (US EPA) trying to keep us from hurting ourselves by adjusting these screws. These caps can be removed by very carefully drilling them with about an 1/8" drill bit. The caps usually start spinning before they are drilled all the way through, and can be pulled out. Under the caps are the screws. The bad news is that if you have already soaked these carbs, you probably already ruined the small o-rings on the screws. The ruined o-rings may be part of your idling problem. These screws (after installing new o-rings, good lick finding them, they also have little washers & springs on them) should be gently bottomed, then backed out about 1 1/2 turns for starters, then out leans (more air), in richens (less air). Finally, the definition of COMPLETELY DISASSEMBLED when it comes to carbs. is unfortunately not a universal one. So, there may be other parts that you failed to remove prior to soaking. If so, and there were any other rubber parts on them they are probably ruined too, sorry. On the choke knob issue. My choke knob doesn't stay up either. Here is how I start mine: 1) turn on ignition, 2) hold in clutch with left hand, 3) pull choke up with right hand (about 1/2 way is all I ever need), 4) hit starter button with right elbow. Once running, adjust rpm with choke in-or-out. After about 1-2 minutes, leave choke go (push in) and ride off. See the rest of the "answers" in the GS Resources page for jet sizing. Is sounds like an art, involving a lot of trial and error to me. What "jets" are what. The "main" jet is the one in line with the "Needle" and the "Needle" goes up-and-down in the brass "Needle Jet" which also must be removed and cleaned after removing the "main" jet. The smaller "jet" under the rubber stopper next to the "main" jet is the "Pilot Jet" and it works with the idle air screw (mentioned above) and with the in the idle and low (about 1/4 throttle) rpm range. The third "jet" you mentioned, the one you say is located on the face of the carb., is the "Air Jet" that meters air flow into the "Needle Jet" circuit. There is a great book on Mikuni carbs available from Sudco. I got my copy from PRO-FLO (jr@pro-flo.com) for about $10.00 (US). I hope this helps you with your GS project...!! The "Needle Jet" can be removed after unscrewing the "Main" jet. I'm assuming that you have already removed the slide with the needle in it out the top of the carb. If you see the brass pin you mentioned below, that tells me that you have the "Main" jet removed and the brass washer under the "Main" jet removed. The brass pin (an indexing pin) holds the "Needle Jet" from turning when screwing in the "Main" jet, it does not hold the "Needle Jet " in place. The "Needle Jet" can be removed by tapping with a wooden dowel (or cut off pencil) from the "Main" jet end. Don't use a brass punch because brass on the brass "Needle Jet" may damage it. The "Needle Jet" comes out the top of the carb the way the needle and the slide came out the top. After removing the "Needle Jet" there are 16 VERY small holes in four sets of four spaced 90 degrees apart up the sides of the "Needle Jet." These must be cleaned/cleared. I used a "wire" out of a wire brush to CAREFULLY poke these holes out on my carbs. DATE: December 12, 1999 First of all, let me say that this is a great web site. I've spent more than a couple of hours going through it and I'm always finding more useful information. Anyway, I'm replacing the stock exhaust on my 1980 GS1100E with a Vance and Hines 4-1 Chrome Megaphone and replacing the stock air filter with a K&N. I know I have to re-jet the carbs but I'm wondering what size of jets I should use. I've never done this before either so I would really appreciate any suggestions and help you can give me. RIDER: Dwayne Van Buskirk REPLY: Scott Horner DATE: November 27, 1999 Jet sizes need for K & N Mod - 1983 GS750 I'm looking for correct jet sizing (and any other carb settings) for a 1983 GS750 with K & N pods. The bike still has the stock exhaust system and Mikuni BS32SS carbs. Settings with the addition of a four-into-one exhaust would be greatly appreciated too. Cheers. RIDER: Stewart Schmidt REPLY: Sandra Whitney Sudco International <sudco@sudco.com> DATE: November 7, 1999 First of all I would like to say this is a great resource keep it up. A question that if have not seen discussed has to do with the emission readings out the tail pipe. This would aid proper adjustments of the carburetor. With an emission analyzer, what should the idle and cruise readings be for the CO and HC. Being an automotive mechanic I can adjust the readings and get the vehicle to run quite well. I have never been able to find the readings for my bike. My bike is pretty much stock but I intend to put on a Vance & Hines and a jet kit. Has the stock air box but has a K&N filter and run with the lid off. Keep up the good work. RIDER: Ron Luckscheider REPLY: Zack Schultz DATE: October 17, 1999 Does anyone know the correct pilot air screw settings for my 650 Kat. The Suzuki manual only lists them as 'preset'. I need some idea of a starting position so that I can sort out the idle. Also I have an problem that I hope someone may provide some advice on. The bike runs fine apart from a flat spot at around 80mph on a steady throttle when it acts as if it is running out of fuel. It clears up as soon as you open the throttle and accelerates fine. It will hold a steady throttle at 70 and at 90 but not at 80. Cheers Steve South Wales RIDER: Steve Waller REPLY: Peter Oxley Question:- Initial pilot screw settings needed - 1982 GS650 Katana Answer :- I have info. on a few types of Mikuni carbs. as follows
Hope that this helps DATE: September 18, 1999 My GS850 idles at 2100rpm MOST of the time which is way too fast. Once in a while it will idle at 1000rpm, which is the perfect speed. I have looked through the Clymer's manual and cannot locate any idle speed adjustment screws. Also, does anyone know why the bike changes idle speeds at will??? I hate to slam it into first idling that fast. Any help would be appreciated. Thanx, Mark RIDER: Mark Oefinger REPLY: Allen Harper In my Clymer manual on GS850G's (first ed. Copyright 1980) it shows up in the Fuel and Exhaust section in photo #30 on pg 127 and in several other photos. I've forgotten which way to turn it, however, and I don't know why the variable speed problem. When it slows to 1000 rpm, why not try squirting carb cleaner or starting fluid around the carbs/manifold etc to check for an intermittent vacuum leak? Also, if this is a cold- start problem, check your float levels to see if they are high enough. Incidentally, for anyone with a '79 GS850G with Mikuni VM (non-CV) carbs, the same knob sticks up at an angle between carbs 2 & 3, above the tops of the carbs. At least as it pertains to MY '79 Model, the Clymer manual is WRONG! It shows the adjustment knob at he bottom of the old slide valve carbs. Maybe it was that way on non-US '79 models but it isn't so on mine and I know mine has not been altered. The knob on the '79 is best accessed from the right side of the motorcycle (as you sit on it) because the choke cable interferes if you try to get at it from the left. Hope this helps. DATE: September 18, 1999 When I am cruising at speeds of 55 plus or the tach is reading 5000 RPM the bike will start to surge. I know the carbs need adjusting. Is this a air/gas problem or can the carbs be out of sync.? Or is it a combination of both? How do you adjust the air-fuel mixture? Do you adjust it by getting max vacuum in each carb? I have never done this before with multiple carbs on a bike before. RIDER: Scott R. Coy REPLY: Frank Perreault DATE: September 18, 1999 I've had my GS for 2 years now and I've been happy with it so far. When I got it, it had been sitting for awhile so I took the carbs off and had them cleaned at a shop. I put them back on and the bike runs good but I get horrible gas mileage. I get about 75 miles to a full tank of gas. Can you please tell me any info on how to adjust the carbs? I think it gets too much gas because if I drive at low speeds for about 10 mins. the plugs start to foul. Also I am aware of the adjustments on the carbs that have caps on them and I carefully drilled them out. Any help on a better way to adjust the carbs would be greatly appreciated. Thank you and keep up the good work on a great site! RIDER: Matt Burcz REPLY: Frank Perreault DATE: August 21, 1999 When I bought my bike, previous owner was using starter fluid to start the bike. He had four in one and foam air filters. Assuming that carburetors were not rejetted I put all stock items back ( 2 two in to one, air box) . Carburetors cleaned etc. Well I am finding that I have to use starting fluid to start the bike also when is cold. After that is OK. What area I need to look in to solve the problem ? RIDER: Wojo Walczak REPLY: Frank Perreault DATE: August 8, 1999 This might be unrelated... but about two weeks ago, my gas gauge stopped working: it stuck in the high position. I didn't attempt to fix it, since the bike itself was running fine. I did notice that my mileage dropped 5 mi/g though. Last week, I started it in the morning and it would only run on three cylinders when I took the choke off; or, the fourth would run only when with the revs >3K rpm. Luckily, a guy I work with used to be a certified Suzuki mechanic. With me telling him the symptoms, we narrowed it down to a few possibilities, the most logical one being that the pilot jet for the #2 (the primary) cylinder (and the one not running right) was clogged. OR that there might be a vacuum leak in the hose leading from the tank into that cylinder. He hasn't had time to take it apart and look at it, so I took it by work (he is on an off-shift) briefly. He listened to it, and thought that it was either the pilot jet for the #2 (the one not running below 3K rpm without the choke on, or the choke might be sticking... so he physically fiddled with the choke slide (which I hadn't done) on the carbs, suggested me spraying lube on the intake manifolds to check to leaks (I did later--- no leaks) and bid me farewell. Strange, but all 4 cylinders were firing after that! What is really strange, and I only noticed it this morning, is that the fuel gauge is working again!! We will try to get to the bottom of this when we tear into it for a valve and carb adjustment, but anyone want to try and guess what happened? I am just happy to have it running well again since it is my only transportation !^)> Btw, all the plugs looked normal when I pulled them. Bought an Electrex to replace my stock reg./rec which had gone out. $60 cheaper than stock one. Chalk up another recommendation. RIDER: Zachary Gemmill REPLY: Joe Amidon I can't see that any of this is related to the fuel gauge. Does this sound right Frank? DATE: July 31, 1999 I am going to have to replace the exhaust on my bike soon. It has been getting louder and louder, and I am now seeing some rust bubbling through the pipes on the bottom of the megaphones. All the aftermarket outfits I have looked at do not show a pipe for my bike. I would like to avoid cheesy generic slip on's that require me to use my old header. A new 4-1 or 4-2 exhaust would be preferred. Any suggestions? (I am in Canada, but if I have to I will import some from the U.S. RIDER: Chris Skanderup REPLY: Michael Batt SECOND : A friend of mine owns an '82 650L and he replaced the stock pipes with a Vance & Hines 4-1 megaphone system and the thing sounds beautiful! It took him all of about an 1 1/2 hours for the whole job. The pipes ran him about $270.00 from Motorcycle Accessory Warehouse. Very good price and he got it two working days later.. http://www.accwhse.com - I recommend it. (Frank: I do too!) Anyway, after he re-jetted the carbs according to the V&H specs. he noticed a big performance boost, but his mileage went down just a little. After a test ride, I was so impressed with the improvement that I ordered one for my '82 GS850! But of course, some of the bolt heads snapped off. Ever notice how nothing goes like it's supposed to? THIRD (and most important): You will need to check the stock gaskets before you install your new pipes. If you need to replace them they will run you @ $4.00 (US) each. Replacing the bolts is also a good idea, but BE ADVISED. Your new manifold mounting plates will not be as thick as the stock plates, and therefore the stock bolts are too long. You will need to get bolts that are about 1/4" shorter than the stock bolts, or you will not be able to torque them down. They will hit the bottom of the mounting holes before they tighten the new V&H manifold plates. I got mine right from my local Suzuki dealer when I got new gaskets. The gaskets, bolts, and lock washers ran me less than $25.00 (US). Good Luck and don't break any bolts! It sucks. DATE: July 31, 1999 What model and year GS 1000 Came with 34mm CV carbs? I have 2 other engines a 78 and 79 that both have 26mm carbs. The engine in question also has visibly larger intake runners cast into the head, and is a chain drive model. Please let me know. Thanks, Russ RIDER: Russ Hankins REPLY: Joe Amidon DATE: July 31, 1999 I have recently taken my GS550EF to the "experts" in order to try and stop the gas from dripping out of the airbox. After 4 return trips after 5 minute rides, the "experts" say that there is nothing more that they can do. They have replaced the needles and seats, adjusted (lowered) the float height, replaces the screens and "overhauled" the carbs. The drain hose conveniently falls in front of the rear tire. It only happens now when I get the rev's up over 7,000. The "experts" say that this was a problem with this model of bike. I got the bike back 3 weeks ago and it still drips occasionally. It smells like it's running rich. I got the bike back, took it out for a 20 minute highway ride and then the electrics went. (At a cost of $800.00) for replacement of the stator and regulator. Is it true that this model has fuel problems? This is my first bike and it seems that the bike is spending more time in the shop than on the road. Can anyone out there help me? RIDER: Bruce Crane REPLY: Gary J. Ward In regards to the dripping problem, my 83 GS550E will drip a little if I have it running on the side stand. I adjusted the floats and the problem has mainly went away (doesn't drip when level). It's fine when the engine isn't running. Check to see if it is running rich by "reading" the plugs (black is rich) or by removing the air filter cover (if it runs better with it off you are too rich). Also check your petcock on your tank and that you have turned in the right direction (not on PRIme) and that all your hordes for your carbs, tank and engine are not kinked, plugged, or missing. The GS550E series is an excellent choice for a first bike. Good handling, nice rush of power at the top end, Great looks and it was one of the best bikes out there in 83-86. Good luck and don't give up! Let me know how it works out. DATE: July 6, 1999 I have recently purchased a 1982 Suzuki GS850 GL that has a 4 into 1 Vance & Hines exhaust system on it. This engine has the stock carburetors on it. (Mikuni BS32SS). I just synchronized the carbs on it today and checked the mix screws on them. It appears that when this exhaust system was put on the bike the carbs where not re-jetted. The option of changing the mix screw setting from the suggested 2 to 2 1/2 turns to 4 turns was taken. With this, the engine runs good to excellent in temps from 80 to 90 deg.. Below this temp range the engine is cooled blooded acting. Should the carbs on this bike be re-jetted? If so what jet size? Do I have to take the carbs completely of the engine to do this? Thank you for your time and help RIDER: David Perreault REPLY: Bill Patten DATE: June 18, 1999 I filled up my motorcycle with gas today and it started to leak out of what appeared to be 5 vent lines from the gas tank. It also started to leak in the area of the intake for the carbs. WHAT HAS GONE WRONG? RIDER: Clayvon Everett REPLY: Frank Perreault DATE: June 18, 1999 I just bought a 77 GS750 for $700. Everything appears to be in good working order. The guy that had it before me rebuilt or replaced anything on the bike that needed it. It runs great. It has a DG Performance Header, a K&N air filter, and has been jetted to 105 mains. The plugs look fine (tan in color). My question is about fuel mileage. I have had it about a week and have averaged 25 to 30 mpg. I thought that this was low. What could cause this? I don't run the bike really hard, but I don't putt around either. It has stock gearing, doesn't leak fuel, has no windshields or anything like that and has been recently rebuilt. I also recently cleaned the carbs, but found nothing out of the ordinary. Both wheels spin freely. Any help would be greatly appreciated. By the way, you have a great website here. RIDER: Cameron Grossl REPLY: Frank Perreault DATE: May 21, 1999 Can my 1977 GS750 be run on unleaded petrol, unmodified, without causing any damage? RIDER: Brian Anscomb REPLY: Malcolm Evans DATE: May 21, 1999 Hello, I'm in the process of buying an 81 GS850G, its a beautiful bike in mint condition with only 17,000 KM's on it. But there's a problem. Its got some sort of after market exhaust on it. I was told by the seller (who bought it last year) that the jets will have to be adjusted every major seasonal change (from our 5-15 degree Celsius in the Spring and Fall to our 25+ summers.) because during the colder seasons the mix is too lean... And he said that his mechanic told him it was probably due to the exhaust. I don't care if the exhaust looks good or there's a minor performance gain or something from it... I'm not going to shell out 250 clams twice a year to enjoy my new bike (I bought it anyways, just fell in love with the damn thing). I figured there has to be a long term solution out there. Thanks for any advice in advance. RIDER: Paul Hohmann REPLY: Malcolm Evans While it is true that bikes run leaner in the cold, the biggest mod I have ever done is to reduce the spark plug gaps from 25 thou down to 15 thou in the depths of winter to aid starting. "Adjustment of jets" even if required would only be as much as turning the air screw in a bit. I'd be interested to know what pipe is on it as usually the
carburetion is quite happy affected unless it has performance
filters as well. DATE: May 21, 1999 Many thanks for your help in the ever-continuing saga of my rebuild project. I thought I had my jetting sussed until the time came for that big first blast - well, it turned out to be more like a small firecracker really! The bike in question is a 1980 GS1000s with VM34 carbs - although I can't seem to find this combination in any of the model guides - and I'm running K&N's with a stainless can 4-1, with minimal baffles. I went up two sizes on both the pilot and main as a starting point but all I'm rewarded with is a 'wall' at 5000rpm. A quick plugchop revealed an incredibly over-rich mixture, so I went back to (what I assumed was) standard jetting on 97.5 mains - with little noticeable difference. Tickover runs rich and a quick flick of the twistgrip rewards me with a white smokescreen obscuring the workshop! The carbs are in bits on the bench right now! Float heights have been checked, the bodies dunked and cleaned (again) and all EPA tamper-proof components have been tampered with, so before I start to re-assemble there's a few items I'd just like to confirm the initial settings for: 1) Idle screws (the ones on top of the float housing). 2) Mixture screws (the ones on the bottom of the float housing). 3) Needle position. 4) The two rubber hoses (1 on #2 and 1 on #4) I thought these were vent hoses, but they appear to be drawing air in - should they be vented or sealed? The pipe on #3 is currently being used to operate the fuel tap. Apart from this (temporary) embarrassing reluctance to run the way it was designed to it's been well worth the effort involved, but I'd like a little more 'go' to accompany the 'show'. RIDER: David Rogers REPLY: Malcolm Evans Stock screw settings can be had from your local Suzi dealer, return everything to stock......after which: First up - you need an air corrector kit for the carbs, you can get these from the same place you got the filters I should imagine. Next: jetting for GS 1000 with K & N filters as follows: 28mm Slide carbs - 110 26mm Slide carbs - 102.5 CV carbs - 142.5 Then: raise the needles a notch if still running lean in the midrange Or just go buy a Dynojet kit, sound like a Stage 3 / 4 could be required to keep it really happy. White smoke? Sure it's not a 2 stroke since white usually means oil, blue is petrol...... DATE: May 21, 1999 I just purchased an'81 GS850GX and the pipe looks like I'll be lucky to get this season out of it. What companies still make pipes for this year and model. I had an '80 GS400ET with a Wolf 2 into 1, does Wolf still make pipes? RIDER: Richard Ries REPLY: Malcolm Evans My money is going on a V&H or a Harris personally for the
1100EZ - probably the Harris as it is half the price of the
V&H!!!. DATE: May 21, 1999 IS THERE ANYTHING THAT I CAN DO TO FIX THE PITTING FROM RUST AROUND THE CURVATURE OF THE HEADER ON A OLD YOSH PIPE. I DON'T WANT TO SAND THE PIPE BECAUSE IT LOOKS TO BE THIN IN THAT AREA. IS THERE A FLAME SPRAY TYPE OF TREATMENT? WHERE THEY SPRAY HOT METAL ON THE PIPE TO BUILD IT BACK UP. ALSO......I HAVE SOME 29 MM SMOOTHBORES THAT NEED RE-BUILDING. IS THERE A RE-BUILD KIT STILL OUT THERE? THANKS TO ALL OF THE PEOPLE AT THE GS SITE........ITS GREAT RIDER: JAMES M FRENCH JR REPLY: Zack Schultz This is the current hot ticket item in Hot Rodding cars as it
also helps to retain heat inside the pipe rather than letting it all
out into the engine compartment (probably wouldn't hurt on our air
cooled GS machines) and the coating will stay looking good for many
years. it's not cheap, but costs less than buying a new pipe... I
was quoted $250 to have the headers on my 79 Nova (2 instead of 1)
done by High Perf Coatings. I would guess that a GS pipe would run
about $150, but that is just a guess. DATE: May 21, 1999 I was wondering if anybody had an idea on a homemade one. Or how cheap is it to buy one? I need to do it since I have had the bike for a year and haven't done it. I also need to adjust my clutch. IT wont grab all the way when I pull it in. IT will still be slightly engaged even though I pull it all the way and the cable has been adjusted to its max. So I believe it has something to do with the clutch basket problems I have heard about. Any suggestions? One other question is how much of a improvement can I see in a new ignition and coil say from DYNA of ACCEL? RIDER: Aaron Zurek REPLY: Ed Parsons So is it worth scrapping a "working" set of stock
coils? If the 3 reasons I listed above matter to you, then I
would. One final reason for changing coils - chances are the
20+ year old rubber on those spark plug wires is probably degraded
thereby affecting performance and gas mileage. In any case, I
guess it's a matter of priorities. [just to show that sometimes I know what I'm talking about.. FP] ;-) REPLY: Joe Amidon DATE: May 21, 1999 I have a GS450T which have recently restored after it sat for about 10 years. The problem I am having is when I give it a little gas and bring it up to about 2000 RPM's, the engine will continue to speed up until it reaches 4500-5000 RPM's. It won't return to idle without momentarily pushing the kill switch or letting the clutch out while it's in gear. I've had the carbs done by the Suzuki dealer. They found a bad float, then they synced the carbs. It ran ok for about 5-6 miles, then started racing again. I saw a similar problem that someone who had with a GS650 on your web site. I E-mailed him and he said it turned out to be his vacuum line to the petcock was reversed with the float vent tube. I checked mine and that's not the problem. Do you think that a clogged float vent would cause the same problem? RIDER: Gary Angelone REPLY: Frank Perreault DATE: May 21, 1999 I recently bought this bike and I think it is great but, I have an old Mac pipe on the bike. It sounds like thunder when I release the throttle. It is rumbling and popping I have looked at the plugs and they seem normal. The pipe does not have a baffle in it, it only has a end piece in it is this sound normal for this pipe? I have no idea whether the carbs have been rejetted or not. if I need to rejet the carbs where do I start and what sizes should I go to the bike also has stock carbs and the stock airbox. I would like to go the K&N's if this is feasible. Your opinion please and THANKS RIDER: James Brown REPLY: James Brown K&N's - if serious about it just get a Dynojet kit while you're at it, otherwise you will need an air corrector kit, then take the mains up a couple of sizes from where they are currently for a start - but an easier method is to get a K&N filter for the stock airbox which won't need an air corrector kit. And won't turn the bike into a twin when it rains. DATE: May 21, 1999 When cold starting I get a backfire (popping) which seems to be coming from pot 1. I have tried adjusting the idle mixture both ways but this made no change. Any help would be great. Thanks. P.S. the carbs fitted have only one screw fitted next to the air box side which I think is an air screw. Also any help on how to stop the back brake caliper from seizing up would be great. RIDER: Gary Chadbond REPLY: Frank Perreault DATE: April 23, 1999 Does anyone know of an exhaust which will fit a 1978 GS 1000 E. I want a Supersport style pipe with an aluminum canister which will allow free flow. Will the header for a newer (80-83 or so) GS 1100 fit on the older GS 1000? RIDER: Troy Pfitzer REPLY: Joe Lanfrankie DATE: March 28, 1999 I know that setting the petcock to prime will allow fuel to enter the carbs via gravity (vs. vacuum) My question: How long does it take to get enough fuel into the carbs in order to start the bike after it has sat for 2-3 weeks? 30 seconds? 10 minutes? RIDER: John Levitsky REPLY: Frank Perreault DATE: March 28, 1999 I have an 81 GS1100 with 25K, Vance and Hines 4-1 pipe although I am not sure if the jetting has been changed. The caps on the mixture screws have been removed so there has probably been some adjusted there. The airbox is stock with a stock filter. The bike seems to run fine although suffers from some hesitation when I ease out the clutch and give in a little gas to go with it. No doubt I will need to rejet because of the pipe but what shall I do to the mix screws? Is synchronization a probable influence? Thanks for the help! RIDER: Keith Viton REPLY: Frank Perreault DATE: March 28, 1999 The bike starts right up no problem, after approx. 10-20 seconds the carbs overflow with gas and it fills the airbox up and starts pouring out of the airbox like a waterfall. I removed the airbox side cover, and restarted the bike. after 10 secs or so, gas starts pouring into the airbox again, this time I watched it happen! floats?? any help is much appreciated. RIDER: Adrian Bowden REPLY: Frank Perreault DATE: March 22, 1999 Recently I jetted my carbs with a DynaJet kit. I also installed a Vance&Hines Supersport pipe. I have had the carbs gone through by a qualified Suzuki mechanic and still I'm having problems getting the dead spots and popping out especially on deceleration. I've checked all vacuum lines for leaks and all my carbs. HELP! RIDER: Scott Henderson REPLY: Bob Frisbie The answer's I got shouldn't have surprised me too much. They said, "It takes a lot of time to get a bike's jetting and pipes just right, and, once you move away from the stock stuff, you better be prepared to spend money (for us to do it) or time (to learn to do it yourself). And, a megaphone exhaust is always going to sputter and backfire a bit. If you don't like it, put a stock exhaust system on it." So, having more time than money, I'm continuing to experiment. I found that moving the needle up a slot has helped some, and, I'm going to buy a carb balancer and give that a try next. And, I've considered searching the bike junk yards to see what's available in old stock pipes. DATE: February 28, 1999 Frank, I need some advice on gas tanks. I've got an 82 GS750T that I bought last fall. It has about 23K miles. The bike runs well so I don't mind investing some money into it. The problem is that I've developed a very small gas leak, almost a seepage on the bottom of the left side of the tank. The tank has got some corrosion visible on the inside as well. I've tried to find a used tank (parts locator service) for that bike and haven't had any luck. I've also tried to buy a new tank from Suzuki. No luck here anymore. 1) Is there a manufacturer of aftermarket tanks that I could use? I'd want a shape similar to stock. 2) Is there a later model, or larger model Suzuki that uses a tank that would fit my bike? I would rather go with a new or newer tank if I can, but if nothing shows up I'll need to get it coated. Let me know what you think. By the way, this site is GREAT! RIDER: Jerry Doolittle REPLY: Frank Perreault DATE: February 28, 1999 I have a 1980 GS 850. Found it all alone in a basement. I rescued it and found it only had 4100 miles on it. A beautiful bike. But....it has been in the shop for the better part of 7 months, more in than out. It boils down to a carburetor problem of some sort. It was thoroughly cleaned, jets changed, electrical system and coil checked out, new petcock installed, and it still runs rich, cylinders 3 & 4 seem to foul quickly, and it has no top end. After the shop thinks they have it perfect, I ride it 25 miles home and it runs great, but let me take it out the next day and it barely runs. I have no way of knowing if the diaphragm has ever been changed. With the low mileage, I would suspect that they are original. On inspection, they look good. Could this be the root of all the problems? A bad diaphragm or 2 or 3 or 4? At a quote of $110 a piece for the diaphragms from Suzuki, I don't want to dive into this project without more research. Either for cheaper diaphragms or somebody with experience with this problem. Thanks, I love the site. RIDER: Lorri McCutcheon REPLY: Malcolm Evans Problem sounds elusive - have you got the correct grade plugs in it? Does the auto advance mechanism for the timing work OK? Other than that it sounds like one of those niggling little faults that takes forever to sort....:-((((.......what pipe are you running? A DynoJet stage 1 kit may be worth trying even with the stock pipes, or get it on the dyno of a race shop, has the air filter been changed? Just a few suggestions. This bike was sitting for a long time somewhere. What kind of shape is the inside of the gas tank in? I have brought several early- to mid-1970's dirt bikes back to life with rusty tanks (most 2-cycles not as bad as the 4-cycles because of the oil mix). I have always installed paper element in-line fuel filters on these. Also, I've noticed that the bikes generally don't run quite right until I've run 2-3 tanks of gas through them. I think that there is some type of chemical reaction with the rust in the tank and whatever additives they put in the fuel now days. At the shop, they generally remove your tank and attach a smaller (non rusty tank) to run the bike when adjusting carbs, etc. This fills the carbs with "good" gas. On your ride home the "good" gas burns out of the carbs in the first several miles. Then, I suspect that the "bad" gas takes a while to foul out the plugs, and it may get worse after sitting over night. It seems that gas with rust in it is somewhat less flammable and harder to ignite (engine floods easier) too. I can't prove any of this, but it might be worth flushing out the tank once a week for a month or so. Or, if the bike is rideable at all, accept the poor performance for 2-3 tanks of gas and see if there is any improvement. Just some thoughts...... DATE: February 15, 1999 What is the best text for understanding the carb on my bike? I have a Clymer but is absolutely worthless. RIDER: Errol Travers REPLY: Frank Perreault DATE: February 9, 1999 Let me start by saying what a great site you have. I own a 1979 GS 750 that I think is in pretty damn good shape and the most beautiful piece of metal on the road, but I'm going through some trouble deciding what to do with the carburetion that I have. I have the original carbs on my bike with a 4 into one Kerker (I think is a Kerker anyway), my plugs are running a little black from the fuel running a little rich. What I'm thinking of doing is running individual K&N filters on each carb to improve the air flow and to reduce the wait of the bike. What do you think, any comment that I get will be greatly helpful. RIDER: Bob Bourdeau REPLY: Zack Schultz DATE: February 9, 1999 I just bought my first bike, a 85 GS550L last summer. I figure it puts me that much closer in my pursuit of the "James Dean image". The Porsche 550 Spider will have to wait. I picked it up for 350 bucks from a guy who had let it set for a few years. I had a friend of mine soak the carbs and clean the jets. After that and a new battery we got her going. The problem now is the middle two cylinders are not firing. Since the outer two are firing fine and that they use different coils I would assume the coils and ignition are fine, right? I took the airbox off and observed the carb slides. They did not look like they were moving very smoothly but the diaphragms are in good condition. Could a weak spring cause the slides not to move up and down sufficiently, causing the cylinders not to fire. If so, where could I obtain new slides. I live in Chattanooga, TN and from my experience the local Suzuki dealers are schmucks. "If only the wealth of information of this site could be incarnated in one man and only if that man could be behind the counter of my Suzuki dealer." RIDER: James Ladd REPLY: Zack Schultz DATE: February 9, 1999 I have a GS850GLT 1981, standard in every way as far as I know. The previous owner said that I should always use 4 star petrol but my Haynes manual says unleaded or low lead is correct. What's the right answer?! RIDER: Paul Walton REPLY: Malcolm Evans they just go faster with 4* in......:-))) DATE: February 9, 1999 My problem is with my Suzuki its a 1980 GS 1100 ET its an American model (80 mph on speedo etc), its only done 27000 from new and is in mint condition. The trouble started when I first got it, at about 5000 RPM, it had a terrible flat spot so I decided to change the standard exhaust for a laser 4 into 1. This made it a bit better so I fitted a dyno jet kit. I had some improvement but it still seemed to be a bit rich until I removed the air filter. It went like a rocket, unbelievable performance but the tick over is very rough and it still has a flat spot. I've tried balancing the carbs several times but to no avail. I would therefore be grateful for any information on changing them completely. I don't want the expense of new flatslides etc so is there a later model Suzuki that has suitable carbs that I can fit? Please help I love this bike and the only thing that spoils it is the rough running. RIDER: Colin Chandler REPLY: Malcolm Evans Either: (I) get a replacement K&N filter for the stock airbox (Dynojet stage 1 with the stock Laser can or maybe Stage 2 if the race can): (ii) go for individual K&N / S&B / Ramair filters for the carbs, Dynojet stage 2 - 3 but you definitely should consider the race can or maybe a Harris with race baffle......... (iii) GSXR 1100 flatslides.......? Push straight on, call up PDQ for jetting info...no I don't have their number, sorry - try MCN? DATE: February 9, 1999 First of all, I want to say thanks for past help. You guys have been one of my most reliable resources. Anyway, let me start of by saying that I have a 1977 GS750 with 9800 miles. It is my first motorcycle, so I'm pretty new to bikes (I've owned it since, September ). 1. I recently took the bike in because the bike seemed to hit a wall at around 5000 RPM's. It turned out one of the carbs wasn't working. The bike was incredible after that was fixed and all the carbs were tuned. The pick up and power was greatly improved. Before this was fixed, I was getting about 34 mpg. Now I get about 28. It makes sense that If there is a whole other carb to feed, I will get worse mileage. But I've read that some of the web readers are getting in the 40s and better. So I'm wondering if I've always had some sort of problem. Like I said the bike runs great so if 28mpg is normal for this old a bike, then so be it. But I wanted to run it by you guys. Also, I'm not sure how much it effects mileage, but the bike has one of those big old Vetter fairings. 2. Well as we've entered winter up here in the northeast, My riding has greatly decreased in the last 3 weeks. The bike is garaged, and I had been starting it every few days. Well about a week ago was the last time it started. The bike cranks and cranks but won't start. The battery is on a tender and is fully charged when I tried. The gas in the tank is now a few weeks old and low but it should be more than enough to start. Being new to bikes and never owning anything with a manual choke, I think I completely flooded the engine. I have no manual so I'm not sure whether I should be using prime or full choke, how much throttle etc to start the bike when its this cold. In the past I always used full choke to start but then turn it completely off. The last few times, I had to leave the choke on and keep the revs high until it warmed up and idled on its own. I pulled a plug out and it is black and wet with fuel. ( plugs were replaced when I bought the bike, about 4 months and 2000 miles ago). Since the bike started just last week, I am pretty sure I screwed things up by flooding the engine and maybe ruining the plugs. I've tried to start the bike two days in a row hoping that time will help evaporate the flooding problem, but with no luck. So any advice on a) what to do to get the bike running again and b) proper starting procedures for the cold so I don't screw it up again. We get a good day here and there and I want to be able to have the bike ready to go. I appreciate your help. RIDER: Osman Yorulmaz REPLY: Robert Del Riego Use full choke. Do not touch the throttle. If you added gas, put the petcock on "On". See if it starts. If it starts, the possibility is that you were lower on fuel than you thought, the reserve position isn't working, you used the prime position inappropriately = you *really* flooded the engine last time. If it doesn't start, the easiest thing to check next is that you have spark at the plugs. If you don't, address that problem. If you do, go back to the fuel system. Remove one of the drain plugs from the float bowls. Gas should come out and it should smell and look reasonably fresh. My 77 GS750 starts right up with gas older than what you have described. If gas comes out and smells/looks right, and you have spark at the plugs, and the battery cranks the engine sufficiently fast, and you haven't diddled with the ignition timing or experimented in any other way since it last ran, it almost has no choice but to start unless there is a question as to compression values, but this last seems remote given your description. If no gas comes out, the bowls are empty and you have to figure out why. This is where you would use the "Pri" position on
the petcock: to fill empty bowls. Areas to check are fuel level in
the tank, petcock position, petcock operation (that is, is it
passing fuel as its supposed to? Pull the gas and vacuum lines, suck
hard on the vacuum hose, gas should flow from the gas line; do this
on both "on" and "Res" positions), possible
clogs in the fuel system from rust or debris in the tank. I
recommend you install a see through fuel filter in the gas line.
This lets you see whether fuel is flowing to the carbs in addition
to catching debris. DATE: January 3, 1999 Let me tell you how much I appreciate the GS Resources web page and all the great information there. I've learned a lot about what to look for while troubleshooting my project bike. I hope to send you a picture when it's done. Let me apologize ahead of time for sending such a long winded message, but I think you'll better answer my question if you have all the relevant facts. Thanks. My name is Robin Adams (male) and I have been a huge fan of 1980-82 Suzuki GS's and Yamaha XS's ever since they came out. I was only 15 years old then and my Dad rightfully kept me off street bikes. It was hard to watch him bike with his friends, but it's probably why I'm still alive today. Anyway, now that I'm in my early thirties, I decided it was time to find one of those great classics and fix it up. I was in luck and found a 1982 Suzuki GS850GL which was in excellent condition, but parked for the past 2 years. It has only 13,000 miles. It would turn over, but not start. I figured it might be a disaster, but what the hey- the price was unbeatable: $750! I have gone through it electrically, even blessed it with an Electrex stator and regulator/rectifier. It also needed a new starter relay. I rebuilt all four CV carburetors (BS type according to Clymer) including dipping the bodies at a dealer to clean out the small holes up and down the needle jet (the dealer called them emulsifying tubes). The bike now starts right up and purrs like a kitten. Now my problem. When idling or in gear going a few mile per hour, I turn the throttle and the engine tries to die. If I keep the throttle open it will. If I quickly release it, it goes right back to idling beautifully. If I open the choke, the rpm goes up and I can get a little more out of the throttle, but as I open the throttle more, it bogs down again until I release it. I can ride the bike through all gears up and down the street as long as I use the choke to give it gas. It seems to be starving when I open the throttle. Yes, no? The slides never raise up even up to 5000 to 6000 rpm, but I can push them up smoothly and they come back down smoothly. I even tried holding them all up and opened the throttle, but the same bogging down/starvation symptoms occur. What have I missed? Nothing changes with or without the air cleaner on. Other things that I've triple checked are the float levels, slide diaphragm for leaks, tried it with the idle adjustment screws set from 2 to 4.5 turns out, and the jet needle setting (it has only one location for the c-clip, so there is nothing to adjust). Thanks in advance for being there to field my query. This puzzler has stumped me. I hope it's a no brainer that you've seen over and over. Have a great Thanksgiving holiday! RIDER: Robin Adams REPLY: Robin Adams Lo and behold, they discovered that the main jets were the wrong size! Somewhere in the bike's history, somebody put in a set of different main jets; perhaps an amateur attempt to cure a fuel/air mixture problem due to clogs somewhere else. The world will never know. But, with the complete rebuild that I did, these different jets became a major malfunction, instead of a fix. With the new proper main jets, all's well! The folks at the shop are impressed by how well it runs for an "old timer." Thanks again, Frank, for the GS Resources question and answer bulletin board. Happy Holidays! DATE: January 3, 1999 I can't get my GS850GZ 82' to run good on # 3. If I put a fresh plug in and run it hard it runs ok. up to 8 g's in high gear. But idle or slow speed it fouls the plug. It has less than 6 k on the bike. I've had the carbs off at least 6 times, and the others run perfect. the plugs are all white on them. I switched the wires with the other plug on the same coil no diff. The slide is smooth and don't stick at all. I drilled the cap on the adj. screw and the adjustment don't help even if you screw it all the way down. I even took the enrichment valve out and cleaned it in case there was trash letting fuel come in around it. Where can that much fuel get past the butterfly when the slide is all the way down and the slow jet is only about 1 turn out from the bottom and the enrichment valve is clean? I used a mercury setup and adjusted the carbs and # 3 has the same vacuum as the others so the valves are alright. Compression is good. if you run it hard it soot's it up instead of wet foul. I've worked on motorcycles for years and years this is my first Suzuki but its driving me crazy. With the air cleaner off and at idle there is no fuel running out even if you leave the petcock on prime. I've cleaned the carb very well and the needle and the seat are good. The only thing that might be a problem is the battery. It starts when hot just fine but it cranks a little long when cold it fouls the plugs slightly. On the Suzuki can a battery have low voltage but still crank but not have enough voltage to have a hot spark? And maybe this cylinder is a little weaker than the others and fouls the plug or I am I grasping at straws . any help out there. I've had old heads Triumph's BSA Enfield's Yamaha's just about everything but this is my first 4 banger and I think I would keep this bike forever if I can get it right. Thanks RIDER: Mike Moody REPLY: Mike Saxon DATE: January 3, 1999 I have a 83 GSX 750 ES which I have just replaced the 120 main jets with 125. I could still do with bigger main jets. I can get the 120 jets drilled cheaper than I can get replacement jets. I am after the diameter of 127.5 and 130 Mikuni jets. The bike has the standard air box, 32mm (BS32SS) carburetors. unknown brand 4 onto 1 with a Transac muffler. If have been wondering about replacing the air box with pods. What would be a good start with the main jets? RIDER: James Boddington REPLY: Scott Horner DATE: December 5, 1998 I have an 81 GS 650 G. This summer it flooded the outside left cylinder with gas so I took it to the local Suzuki dealer to have the carbs gone through and a general tune-up. When I got it back, the gas mileage had gone from 35 to 50 mpg. That in itself is probably a good thing if it were not for the side effects. It now runs much hotter, uses more oil, has a significant power loss, pings on lower speed roll on acceleration, and is generally a pig as compared to before the tune-up. The guys at the shop have checked a couple times since and say everything is in factory specs. I always use premium fuel in it. This thing won't perform as well riding single as it used to with me and the wife both on it. What went wrong? RIDER: Dale L. Hochstetler REPLY: Frank Perreault DATE: December 5, 1998 With a little help from GS Resources I traced the problem of fouling the #2 sparkplug on my 1982 GS1100E to a bad diaphragm in the Vacuum operated fuel petcock. I clamped the vacuum hose shut and I'm running in the "prime" position on the petcock. Problem: I'm on a very tight budget and the Suzuki dealer wants $70 for a new petcock and the parts breakdown doesn't show a diaphragm. Is there an inexpensive fix? I'm considering attempting inventing a replacement diaphragm but I'm hesitant to disassemble my petcock without parts in hand, if the diaphragm crumbles will the petcock leak? Is the diaphragm replaceable and where can I get one? Can I fabricate one? Any ideas? RIDER: Frank Perrine REPLY: Scott Horner What I found: In my petcock there is the position for prime and run only, no reserve on my model. There is a little spring contraption that regulates the diaphragm position inside and it had become bent and inoperable in the run setting. I figured out how it was supposed to be and just bent it back, running fine ever since..... DATE: December 5, 1998 I have an 82 Katana that has been garaged since 1992. The bike is stock. I completely went through the carbs and replaced a defective coil in the past week. It idles fair, when I open the throttle quickly I seem to have blue/gray smoke. Slow twisting of the throttle produces little or no smoke. The carbs are closely synchronized. Sounds good till you rev motor past 5500rpm. Although there is some faint popping noise that comes from the left exhaust pipe during slow throttle acceleration. At first I thought the float level was set wrong, I verified and adjusted - the problem persists. All four cylinders are running strong. I have a remote fuel tank that I normally contains half a gallon of fuel, it sits about a foot higher that the carbs. At 5500rpm, the problem sounds like it is bogging. It will not rev past that ceiling. The Suzuki owners manual has 17 reasons for poor high speed operation, the one that I fear is bad valve springs. I opened up the valve cover and there seems to be no noticeable wear on the cams. I have also checked the advance mechanism on the crank, it is advancing. Thank you for the site and any help you can offer on this problem. RIDER: Vicente Vargas REPLY: Henry Dedrick I'm not sure which part of the carb it's on at 5500 unloaded, but this sounds like the fiasco I got myself into when I tried opening up my needle jets with a drill. I still idled OK, but as soon as the carbs airflow activated the vacuum pistons (mine are CV carbs), then the engine would start to drown in the resulting very rich mixture. Or maybe you could have some kind of an ignition problem only apparent at this RPM? DATE: November 1, 1998 Terrific website! It's great to have a place for those of us who ride and appreciate these timeless motorcycles. I have a 1981 GS 1000G. The engine is stock. It has a V&H ProStock exhaust (drag racing): four pipes sweep out to the right and down, back into a megaphone that runs straight back low along the frame on the right hand side. The airbox is stock, with a K&N air filter (although the "snorkel" that runs up under the seat has been removed). The carbs are stock, but have been rejetted. The previous owner did not know the size of the current jets, nor if the pilot/idle jets had been replaced as well. The bike ran well, but not until fully warm, and had a rough/flat spot at about 3000-3500 rpm. I raised the needles in the carbs with thin washers and this greatly reduced the warm-up time and helped with the rough/flat spot. Here's the question. The V&H pipe is rusty and detracts from the otherwise pretty clean condition of the bike. I'd like to replace it with a new, more conventional V&H (or any other quality brand) megaphone. My concern is that the new pipe may alter the airbox/carb/exhaust pipe status quo. Can anyone recommend an "off the rack" combination of aftermarket pipe, carb jetting and airbox combo that I can install that will be pretty close to optimal, so I don't have to reinvent the wheel and spend a lot of time finding a new air/fuel/exhaust ratio. If I need to trash the stock airbox and go to dual or individual air filters, that's ok. I would prefer a combo that improves low and midrange power; the bike's got a shaft drive, so boosting the top speed is probably out anyway. Any help or advice will be greatly appreciated. RIDER: Robert DePriest REPLY: Zack Schultz DATE: November 1, 1998 I own a GSX750 1980 (or near there ) bike. Cause I used my bike only for touring and holly days it remains for long periods at the parking. when I try after a long period (2-4 weeks) to run the engine it fails cause of fuel supply, the battery it is strong or I used my cars strong battery ). I have noticed that the gas filter, (between the tank and carburetor) is totally dry of gas. Even when I used the free gas flow position, the filter doesn't feel in. After 3 hours the gas filter full in the middle with gas. The gas pipes are new. So, is it a carburetor problem ? RIDER: George Karakitsos REPLY: Frank Perreault DATE: November 1, 1998 First, let me tell you that this site has more tech info than all the other motorcycle sites I've visited put together. Keep up the fine work! I recently acquired a very low mileage (11K kilometers) 1979 GS750L. fitted with Mikuni slide carbs. My question concerns the vacuum petcock. Although the bike was running when I bought it, the idle was rough. I carefully cleaned the carbs, and the decided to check the vacuum petcock. When I took the petcock apart I found the closing spring was on the wrong side. i.e. it was keeping the port open. The petcock vacuum hose was connected to what seems to be the atmospheric vent on carb #2. The only other hose on the carbs is the fuel hose. As there is (surprise) no vacuum at the atmospheric vent on carbs 2, 3 or 4 where is the vacuum source for the petcock ? The bike runs, but the petcock is bypassed. Your help would be greatly appreciated. RIDER: Nick Wakefield REPLY: Frank Perreault 1. I discovered that only the #3 carb "vent" tube on the on this bike is where the vacuum source is. The vents on carbs #2 and #4 do nothing. (there is no vent on #1) 2. Rough running. The previous owner had the local power boat shop clean out the carbs after the bike had been idle for a couple of years. Since the bike was running very rich (and rough) I carefully cleaned all the passages, orifices, jets etc. and checked the floats......three times. Then I decided to look at the jet needles. After 25+ years of owning all sorts of bikes. I thought I'd seen everything. WRONG!!!!!!!!!! The jet needles had been cleaned (attacked) with what looked like 80 grit sandpaper. Judging by how narrow the needles were, the "tune-up" specialist made sure that all traces of gunk were thoroughly removed. $68.00 + taxes for 4 new needles and the bike runs great!!! Keep up the good work! As for the damaged jets - I've heard and seen it many times. The measurements of the jets is extremely critical yet people think they can ream things "just a little" and think that it will have no effect. Wrong! If the jet can't be cleaned with a toothbrush, a small air paint sprayer cleaning brush and paint thinner, then just go buy another jet. (It should come clean with these things however.) The problems caused by a reamed out jet just isn't worth the trouble. DATE: November 1, 1998 I purchased a 1981 GS650, shaft drive. Before I bought it I road tested it and I ran fine. I trailered it home about 2 hours. When I went to start it a few days later gas was coming out of the vent hose for the two right side carbs (Nos. 3 & 4 I think). I have read your answer to another problem similar and checked the vent hoses. All o.k. The spark plugs on these two cylinders also become fouled and smoke comes out of the exhaust pipe. I took the carbs off, cleaned them out (did not o-haul complete). It now runs without any gas coming out of the vent tube, but the engine is missing. The problem now is it seems to be missing from both sides where as before all of the problems centered around the right side only. I think that I am looking at a couple of problems here, but I can't figure it out. I do have good spark at all of the plugs. Thank you for any help or direction you (or someone) might give. RIDER: Tom Dwyer REPLY: Joe Amidon DATE: November 1, 1998 For reference, I submitted a question back on August 24th. I've tried just about everything I can think of to correct my problem, including the suggestions (answers) for my original submission and I still have plug fouling. I thought this problem would be easy to solve. I either have too little air going in, or to much gas going into the carbs. The bike is all stock, so I've been battling with the fact that I shouldn't have to rejet to correct the mixture problem. I'm assuming the bike ran ok when it left the factory so I shouldn't have to change jets or anything for that matter. Well, in utter frustration, I pulled the air filter out, and left the side off the air filter box. The bike really came to life and ran great, but of course, I can't leave the filter out and the air box open. I put K&N's on, and the bike was good enough to ride, but the plugs STILL were black, but not as bad as before. In desperation, I've rejetted from 115's to 110's to 100's. All 4 plugs are still black but not as bad as before (with just K&N's). The bike runs a bit better, good enough for city and highway, but still hesitates starting from idle and is only getting 30mph. What could possible cause a stock bike to run soooo rich, even after the airflow has been significantly increased, and jet sizes reduced by several steps? I've cleaned the carbs at least 4 times now, idle set at 1.5 turns etc, etc etc. I've quadruple checked floats, even had a shop double check my float adjustments. I've even replaced all the floats. Could this be due to a weak electrical system? If so, what component should I replace. HELP!!!!! RIDER: P. Chris Whyley REPLY: Tracy Presnell Since CV carburetors rely on the movement of the slide for main-jet regulation, which is independent of the position of the butterfly, this movement must be influenced by several factors. Vacuum, as well as air flow under the slide, will influence the position of the slide and also the position of the metering rod. If the springs above the slide have weakened with age (assuming there are springs), or possibly even broken, the slides will be farther up for any particular air flow through the carburetors. Even with a downsizing of the main jet, if the metering rod is too high for a particular air requirement of the engine, rich running could result. I would check to see that the slides are returning easily and fully to their most downward position when the engine is off. If you push the slides up by hand, they should return to the full down position quickly with no stickiness under their own weight and spring pressure. With the air filters off and the engine running, they should move smoothly and evenly up as the throttle is turned. Any jerkiness or sticking (especially returning to the down position) could cause an overly-rich condition for any particular engine speed below WFO (wide full open) at which the metering rods are of little or no value to jet flow. Also, you should check for any vacuum leaks in the slide operation circuit. If there is a hole or slight leak in the slide diaphragms (assuming there are some), the slides won't be in the correct position relative to engine air flow. You noted that the bike stumbles off-idle. If the slide is too far up, the transfer from idle circuit to running circuit (regulated main jet) will not be smooth resulting in the noted stumble. You also noted that removal of the air cleaner caused the bike to run well. While is has been my personal experience with my 82 GS750 EX that removal of even the lid to the air box won't allow the bike to do much passed about 2000 rpm (both the idle and main jetting can't handle the increased air-flow), your bike may have been jetted a little richer from the factory. Also, without a less-restrictive exhaust, you may not be getting the full effect of air cleaner removal or the change to K&N's. You might also check that the jets in the intake throat of the carbs are clean. I don't know the names of them but I do know that they do provide some air into the fuel flow. A blockage of these jets could also result in the rich condition you describe. One other thing. You said that you changed the floats, but how were the needles and seats? Do the needles move smoothly in the seats? It is a pretty close fit and even a slight fuel gunk buildup could cause the float level to be too high. I would suggest a dose of one of the more powerful in-the-tank carb cleaners. This may be enough to loosen up any deposits in the fuel contact parts. It won't, however, clean the small air jets in the throat of the carbs. These will need to be cleaned by hand with a spray carb or brake cleaner solution. Good Luck. Let me know if any of this works. I hope to have my GS on the road again by next spring. It sat for 6 years and I'm doing a pretty thorough redo including rust removal (a quart of chrome cleaner), repainting of most of the removable parts, aluminum swingarm from an 1100, new fork seals, rear shocks, chain, smaller front sprocket, etc. Ain't it a blast? DATE: November 1, 1998 I just bought this bike and it had been sitting who knows how long. Having trouble getting it running smoothly. The Q&A on fuel/exhaust I think will be extremely helpful. Question is: What gas mileage can I hope to get with this bike? I'm sure the 30mpg I am getting now is on the low side. I hope! RIDER: Lorri MCutcheon REPLY: James Boddington DATE: October 4, 1998 I have rebuild my 1980 GS550E after a serious engine problems using a GSX750F engine, GSXR 750 front suspension, FZR 600 rear suspension, etc. Bike now handles great, but the last 1.5 years (ever since I rebuild the bike) I'm having serious mixture problems. I was able to solve some, but I can't seem to get the mixture right ! Can somebody out there please help me with the following questions: ???
Does anyone out there have some experience with this ? What colour does the air-filters need to get after I sprayed them in again (dark-, medium- or light red ?). Is it possible to mess up the mixture by spraying too much oil on them ? Is rain a known problem with these air filters ? Please help me out !! RIDER: Johan Thijs REPLY: Frank Perreault Yes, K&N's soaked in lots of oil will affect the mixture, typically by making the bike run rich. Remember, you are now reducing air flow to the engine (air + fuel = power). So the goal is to get the filter sprayed so they are medium red, not soaked. That way it you go slightly overboard it should clear out after some riding. If you soaked them by accident and you are trying to adjust the carbs, just take the filters off. You should be able to set the mixture at idle. Just remember to put the filters back on when you're done. And rain should not affect the filters unless you are riding
in a monsoon (water and oil don't mix). This really helps me, I will start working on my bike this afternoon using your suggestions. I'll keep you informed about my progress. You have never heard of K&N's / mixture being affected by rain ? What happens when the rain is falling on them ? My suggestion is that the holes in the cotton, where normally the air flows through, get filled with water. Some of it stays there (making the mixture richer), but some of it gets burned in the engine. After a while of driving trough the rain my exhaust pipe sounds different because of all the water damp getting in the damping material. Funny thing is that in idle situation the engine runs better than in the dry (less damping in exhaust -> mixture getting leaner). If I don't spray in the filters with enough oil the cotton gets soaked by the rain as well. In this situation, my bike even runs like #%*&^^% in fog. What do you think about my findings ? Do you have any other
suggestions ? Thanks very much in advance. Now, fog is a different matter completely. Have you ever heard the term that "fog is a cloud stuck on the ground"? Fog is a vapor (air at 100% saturation), and it will readily pass through the filter. There is nothing that you can do for that circumstance. DATE: September 26, 1998 I recently topend rebuilt a GS850 and everything is fine except that I can not get the carbs to function correctly. Two problems:
I did take apart and clean the carbs and I thought I had put everything back as it was. The manual is exceeding vague as to details of the hose setups and of the carb internals. Can you help and/or where can I get a detailed carb setup and installation description? RIDER: Tom Burger REPLY: Pete Peters And yeah, it won't run worth a damn if these aren't there! DATE: September 26, 1998 I've got a 1981 GS550L with 4200 miles on it that just isn't running good enough to take on the road. I'd like to repair the bike myself but am not an expert by any means. Here's the symptoms: The bike usually starts when its cold. The rpm's waiver from about 1000 to 3000 slowly, going up and down every few seconds when cold. The bike will idle only above about 2000-2500RPM. When the idle screw under the carbs is adjusted there is a point where the idle goes up to 2000-2500RPM. If brought back (turned counterclockwise) even 1/4 turn from there the idle will go to 0, especially when the engine is warm. I can get the engine to idle at 1200-1800 rpm for a little while when the engine is cool. If the throttle is hit and then released, the rpm's go up and stay there for a few seconds before coming down. So shifting gears is difficult as the rpm's don't come down between shifts. This happens whether cool or hot. If the bike is shut down after warm-up it won't start again until it cools off even with the throttle turned all the way and/or the choke out. It sometimes starts with a squirt of starting fluid into the air intake under the seat. I notice that during idle, the left side exhaust is a little sporadic compared to the right pipe, especially at low idle. The person I bought the bike from last fall put some sort of red goop around the engine side of the intake boots. There is also a wire twisted to each intake at the engine. I can't see how to get a good seal around these boots and don't think his work did the trick. Each boot has only one screw holding it on to the engine. How can this hold the boot tightly around the intake? By the way, the bike didn't run so good when I bought it either. But it's such a clean bike and the price was right, how could anyone pass it up? What I've done: -Cleaned the fuel line filters in the tank. -Checked the valve clearance. Measured 0.0015 inches for all intake and exhaust. -Took apart the carburetors and soaked/brushed all the jets with carburetor cleaner. The Clymer manual doesn't say much about what else to do with the carburetors. There was a lot of green buildup on the far left carb jets, but the others looked pretty clean. After putting everything together again, the bike ran about the same, except the rpm's didn't oscillate as badly. Any suggestions? RIDER: Ben Carlson REPLY: Michael Saxon DATE: September 26, 1998 I acquired a GS1000G from a friend. When I first started tinkering with the bike it wouldn't run. I drained all the bowls in the carb and tried again. Now it will start only with the choke wide open and then it only runs for a few seconds (maybe 30) then dies. If I even touch the throttle it kills. Does anyone have any ideas? Thanks. RIDER: Andy REPLY: Frank Perreault Another thing that can be used are brushes used to clean
orifices in compressed air paint guns, (Binks & DeVillbis
guns). These guns also have very small orifices and the
brushes are designed to clean but not damage. When these
brushes are used with carb cleaner they work well. Any good
automotive paint/auto parts dealer should carry these brushes. DATE: August 26, 1998 I recently bought a 79 GS850 but the previous owner left me with 3 hoses coming from the carburetor that are just hanging there. I know which one is the main fuel hose and that the 4 coming out of the bottom just route down under the frame. From what I've learned at your site so far one of the 3 mystery hoses supplies vacuum to my fuel petcock valve but which one and what about the other 2? If you can help I'd really appreciate it. By the way I found your site while I was considering buying my present bike and helped me make an informed decision to buy it. You have a great site here! Thanks! RIDER: Edward Seal REPLY: Frank Perreault DATE: August 24, 1998 I own a 1979 gs750e. I keep fouling the spark plugs with carbon. I used a champion plug with a nc3 heat setting. Is this the right plug? Also I don't know if the carb pilot settings are right. They are both turned out one full turn. What should I do? RIDER: Milt Groelinger REPLY: Frank Perreault DATE: August 24, 1998 Before getting to my problem, I'd like to also say that this is a fantastic Web Site. Being able to read about other people's technical problems and solutions makes bike repair and preventative maintenance much easier. The rest of the site has fantastic info on just about anything I can think of. Outstanding!!! My problem: Carbon fouling on all 4 plugs. I just serviced the carbs myself;
chem dipped (no rubber or plastic), compressed air through all
channels, new gaskets, seats, needles, adjusted the floats etc. I'm
happy to say that the bike started right up after priming it. The
throttle is very responsive with no hesitation (I've only taken it
up and down the street 35mph max), but it idles rough. I pulled the
plugs and found them to be dry and black. I cleaned all 4, put them
back in, and started the bike up. It idled a little better, but
still wasn't smooth. I took it up RIDER: P. Chris Whyley REPLY: Michael Saxon When I cleaned my carbs I totally disassembled them and dipped them in carb dip. The kind that comes in a can with the little basket. I then cleaned them in gasoline and also blew them out with compressed air. When I put the carbs back together and tried to balance them I couldn't get the bike to run at a steady speed and it was running VERY rich. Hence the black fluffy deposits on the plugs. Mine was so bad that a couple of the pipes turned a yellowish color. Anyway I pulled the carbs again and checked them out and rechecked my float settings. As far as float settings go, the setting should be done with the float bowl gasket removed and I checked mine on the very end of the float right before it starts to curve down. I believe the setting is between .840 and .920 in. The manual should give you the correct setting. And yes the needle should be closed at this point because this is were you want the float to be at to close the needle and seat. Without getting all drawn out in the whole process of all that I did to these carbs I can tell you that I made a serious mistake. I did not pull the idle mixture screws out when I dipped the carbs. In the front of the carbs (manifold side) on the top you will notice these silver looking caps with little holes in the center. In you carb kits that you got there should also be these same silver disks. Underneath these caps are the idle mixture screws. At the end of these screws are little rubber O-rings. In my case what was left of these lil O-rings. When I dipped the carbs, the dip pretty much destroyed these O-rings and I had to re-clean them all over again. Also one very important point. DON'T TRUST the compressed air to get the dip out of the channels in the carbs. After I dipped and washed with gas, I also got a few cans of carb cleaner, (K-Mart el cheapo brand) and used about a can on each carb. This info I found on this GS resources page. (Thanks Guys!) Well after I did all of this and did a balance and a proper set on the mixture screws, (1 1/2 turns) the bike now runs great and better than ever. It may take a few miles to blow out any leftover residue in the carbs and such but after a few miles it will be fine. I rechecked my balance after about 30 miles and it took a little adjustment but not much. Runs great. A couple of points to remember. When you take the caps out to get to the mixture screws be VERY careful. I had to drill mine out with a small drill bit and a lot of patience. When you get about halfway through the cap with the drill it might start to turn. If it does pull it out, bit and all. If it doesn't, you will hafta use an easy-out bit. DON'T go to far with it because the mixture screws are right underneath these caps. Also DON'T lose the little O-rings for the mixture screws that come with the kits. I did (stupid thing to do) and I had to PAY $6.00 a piece for new ones. So good luck with your project and I hope that this helps in some way. DATE: August 24, 1998 This bike had been sitting for three years out side because the previous owner parked it when the engine began to make a great deal of noise that turned out to be a loose timing chain. I pulled the tensioner and reset the spring and that stopped the noise. As long as I had the carburetors off I dropped the fuel bowls and cleaned the jets that I could get to easily. After putting it all back together the bike starts on the first few cranks of the engine with the choke off and not touching the throttle. If it does not, then no amount of playing with the choke or the throttle will get it to fire, but if I squirt a little starting fluid in the air cleaner it will start. Upon starting it runs rough until warm then seems fine but after a few blocks of riding the idle begins to run up on its own from 1K rpm up to 3 to 4k and stays there unless you load it down by clutching it and then it stays low until you open the throttle above 2 or 3k rpm and then it runs up. If you readjust the idle at the carburetors with the thumb screw you cant find a position that keeps it idling that also doesn't cause this jump in rpm. I have tried to find a vacuum leak by squirting starting fluid around the carb. area but there is no response. Any ideas on how to get it to idle? It runs fine other wise and you can run through all the gears and not notice a problem until you pull up to the first stop sign and then it will not drop down unless you load it with the clutch. RIDER: R. William Mace REPLY: Frank Perreault DATE: August 24, 1998 I just bought my 1977 GS750 last December. I bought a yosh pipe for it and installed it, I have cleaned the carbs and synchronized them, but haven't done any other mods yet. It seems like it may need larger jets (it runs sluggish when I really get on it, but when I use the choke, it seems to run much smoother. I am also considering a K&N filter. Please tell me what you think. RIDER: Rick Wessley REPLY: Frank Perreault DATE: August 24, 1998 Hi! Thanks for past help with my carbs. But now new problems have arisen. If you don't remember, I had trouble starting my '82 GS850L. Well, since then I have had a competent shop take care of that problem, but like I said, I have another plug fouling. I have replaced the battery, air filter, and a total carb rebuild. I've checked the compression and it's even all the way across at 140 lbs. I've even tried 2 different kinds of plugs, Split fires and regular ones. If I remember, I gapped to my manual at .028. Any and all help would be appreciated. I'm at a total loss of what to do besides taking it back to a very expensive dealer (Can't anyway, no $$). Another thing I'm wondering about is the timing. That's what I think it is. Is there anyway to check it? My manual doesn't mention how to check it anywhere. Has anyone else out there had this problem? If I can't fix it myself., I think I'm going to have to sell it. Does anybody out there have any Idea what a very clean 1982 GS850L go for? It's got a ton of new parts and still holds a great shine since it's only got 17,000 miles on it. I hope you can help because I'd sure hate to get rid of one of the best bikes I've ever owned. RIDER: Dave Goldstein REPLY: Joe Amidon DATE: August 24, 1998 I just bought an 82 GS1100E with a Vance & Hines 4 into 1 and was told it was rejetted although the stock air box was still on. It seemed to be running rich so I put some Uni Pods on. This made it way to lean. Any suggestions on what jets to get and where to get them and how to put them in? RIDER: Tom McDonald REPLY: Frank Perreault That is of course, if you've still got the standard 34mm Mikuni's. Rumor has it that the 82 GS Eleven goes like stink if you put the 38mm flatslides from an early GSX750R on. they are told to fit like they were meant to be there from the beginning. However, I have no experience with this myself. DATE: August 24, 1998 My mechanic told me the problem with the bike is the K&N air filter and I can only avoid this by replacing the K&N filter with the original filter. What do you think? RIDER: Maurice Post REPLY: Frank Perreault I discussed this with some of the experts that hang around here and it made no sense to any of us. After all, we are running both older and newer Suzuki's with K&N's and are having no problems. The person that brought this subject up originally claims that once he went back to the original airbox arrangement, his bike ran fine. So, I don't know what to tell you. The 'experts' don't
understand it, but there are claims supporting your mechanic's
statement. If your bike is running crappy, you may want to go
back to the original airbox arrangement and see if that fixes
it. And yes, you need the original air filter and the original
airbox. The story is: IF you apply K&N's instead of the original airbox and do no other modifications, the bike will run crappy. If you apply K&N's, and you modify the jetting accordingly, going back to the standard airbox will mess it up as well. The K&N's will increase the air flow into the engine at a given engine speed, and therefore the jetting will have to be modified in order to prevent the bike from running poor. (poor as in "too little juices in the mixture") Any good GS1000 will almost certainly increase BHP by something between 5 and 10% OVER THE WHOLE REV RANGE if you dump the standard airbox, apply K&N's and get the jetting right. A Dynojet Stage 3 kit's standard recommended settings and jet sizes will come close enough if you don't have access to a Dynojet bank, especially if your GS is at standard capacity. If it has a big bore, you would want to DECREASE main jet sizes, since the bigger capacity would such harder at the standard carburetors. DATE: August 24, 1998 I have a 1981 GS850L with 11,000 miles since new. Just recently it's taken to fouling the #2 sparkplug after only about 100 miles of local driving and the gas mileage has been poor. My suspicions are that I somehow got some dirty gas and my #2 cylinder is running much too rich perhaps from the needle valve being stuck open. The engine burbles at a steady throttle position although not when accelerating. Is there an easy way to check if this is so without a total dismantling of the carburetor? RIDER: Irving Stone REPLY: Frank Perreault DATE: August 24, 1998 Is it OK to run my 1981 GS550E on unleaded petrol/gasoline? I've heard that engines designed for unleaded petrol have hardened valve seats but don't know if my GS550E has these. RIDER: Neil Battersby REPLY: Zack Schultz DATE: August 24, 1998 Where can I find replacement pipes for a GS550E. I'm not worried about the pipes being stock, however J.C. Whitney and the like don't go back to 1979 on pipes. Also, cleaning out rust in a tank. I was told by an old Navy guy Kool-Aid works? Does it? Where to take it to have it cleaned. RIDER: Renee' Schmidt REPLY: Frank Perreault As for the rusty tank, check out the various articles in Q&A - Fuel/Exhaust. You're not paying attention now are you? ;-) DATE: August 24, 1998 Need a little advise from a carburetor wiz (or two). I've got an "83 GS1100E; 4-1 exhaust, an off brand, glass packed megaphone; Uni Foam filter with stock box (top lid removed); and a jet kit. I cleaned the heck out of the carbs before I put in the kit. This bike had been sitting for 10 years in a garage and so I don't know how it ran before I got it going again. Problem is some rough running at cruising speed. I either downshift to keep the revs up or upshift to let it idle to avoid the trouble. It backfires through the exhaust and misses (just a little bit). The bike idles real well, and accelerates pretty good, and, when I get it going, it runs fine. But, unfortunately, not all of my driving is going to be at 80. I think its the pilot jet maybe. And, I think what I need to do is (1) Put the old Air jet back in (I installed the one from the kit), and (2) lower the main jet needle one slot. Am I doing the right things? RIDER: Bob Frisbie REPLY: Michael Saxon However, (as you know) missing and backfiring can also be caused by a lean mixture. Have you checked the exhaust gaskets? If it's an off-brand pipe, it may not fit very well, and you may be getting a fair bit of leakage at the header. BTW - I found out what was causing my "fuel starvation" problem with my GS850 - the coils were .7 ohm (for CDI Ignition) rather than 3 ohm. Accel mislabeled them. I don't know why this causes the bike to sputter and die, but it does. (See below.) Couple of things: Have you replaced the fiberglass baffle? On my GS750E with
V&H 4 into 1, I changed the baffle every year - they get crudded
up with exhaust by products -> more backpressure -> runs rich
-> unburned fuel goes boom? Other possibility - how well does the
off-brand pipe fit into the head? If there is significant leakage at
the exhaust gaskets, the additional air in the pipe will definitely
promote backfiring. If you have a bigger bore, you'd go DOWN on main jet size, since the bigger pistons suck harder at the inlet side. But when this happens at 80 mph, we wouldn't look at the main jets, we'd look at the needle! With a small load, the form and position of the needle is much more important than jet size. Experiment with this first. If it's too rich, then indeed lowering the needle would be in order. And if you really want some benefit, dump the standard airbox
and fit 4 separate K&N's (don't forget to up the main jet size
to something like 138 if you decide to do so). DATE: August 24, 1998 I am having a right old time of it with my 1982 750SZ Katana.
When I ride the bike it is fine for the first 5-10 miles, and then
it becomes very sluggish when I open the throttle, feeling like it
is running low on petrol. This is also a problem when pulling away
having stopped, the I have attended to the following:
The symptoms of this problem all point me to a fuel starvation. Do you have any other ideas as to the possible cause? Could it be electrical? Any ideas would be gratefully accepted. RIDER: Tristan Shanahan REPLY: Michael Saxon Forgot in the last post. Try taking it for a ride with the fuel cap loose to see if you are building a vacuum in the tank. Best with 1/2 tank or less so you don't slop fuel into your lap. DATE: August 24, 1998 My question is my bike starts fine, it needs a little choke, but won't rev above about 2500 to 4000 rpm. I have a set of K&N's with a V&H pipe. I haven't rejetted it yet though. Also the vacuum plungers in the carb bore flutter but nearer completely open. Is it just running really lean or do I have a vacuum leak. The only vacuum hose I can see is the one from the petcock to the carb assembly. My other question is Have you heard of a thing called a "Dial-a-Jet"? I saw it in a Dennis Kirk catalogue. If that thing is bogus then can you tell me where to find a Dynojet kit. And finally, do you know of some company or catalogue that may sell new high performance parts ( Cams, rods, cranks, bigger valves, etc.). Thank you in advance, You have a GREAT page, I have found it very helpful, so thank you very much. RIDER: Jack Love REPLY: Frank Perreault DATE: August 1, 1998 This is your pal Brian Underwood . I think you were talking about my Techs advice to go with the stock airbox Vs 4 K&N's I am using a K&N in the stock airbox 120 main jet bike runs great 2nd gear wheelies. But I do think you know what you're talking about ( most of the time). I have one other question. When I went to back to the stock airbox w/ the K&N I've developed a ping (timing type) I run brand name high octane fuel is this air/ fuel mixture related. It's not a real bad noise but it's one I could live without. REPLY: Brian Underwood Try adjusting the timing and see if this does anything. You may also want to check the adjustment of your valves. DATE:
July 13, 1998 Hello, I was wondering if anyone with a 80 GS 1000g has had this problem. I recently cleaned my carbs being the bike sat for a couple of years and now the idling is rough under 3000 rpm and it smoothes out and is strong after 5000 rpm. Thanks in advance. RIDER: Bruce Brockel REPLY: Michael Saxon No offense, but it sounds like you've still got crudded up idle passages. It takes more than compressed air and Berryman's to get rid of the varnish in there. My favorite method is to get the carb cleaner from NAPA that comes in the paint can. In it is a dip basket. Disassemble the carbs completely (this stuff will dissolve rubber), and soak the parts from each carb for at least 30 minutes. Then go crazy with compressed air through every orifice you can find. As you put the carbs back together, be sure that all the idle screws are set correctly, and that the float heights are adjusted (just a few mm either way can really screw up drivability). As you put the carbs back on the bike, make sure that the intake manifolds look good, without any cracks or cuts where air could seep in. Then, do an idle drop to set the idle mixture, and balance the carbs. Going slow, this whole procedure took me a good six hours, but I cleared up a very annoying idle problem that compressed air alone couldn't fix. DATE: August 1, 1998 I have what sounds like a clear fuel starvation problem, but I'm looking for other explanations. My 81 GS850G was the victim of a hit-and-run, resulting in a dented fuel tank and mangled controls. I've since fixed the controls, and installed new Accel coils and wires (along with new plugs, fuel filter, oil, gas, and a charged battery). Problem: Although the bike starts easily and runs well initially, it starts sputtering after 1/4 mile or so and eventually dies. It will restart after it sits for a few minutes, and then repeat its slow death. The inline fuel filter reveals that fuel is leaving the tank, and removing the gas cap doesn't help (not a venting problem, apparently). The second wrinkle is that I had a shop replace the handlebar and controls (insurance picked up the tab), and the bike seemed to run fine on the two mile ride back from the shop. So, I'm trying to figure out what I might have screwed up to create an ignition problem that presents symptoms just like fuel starvation. Any insights would be much appreciated. RIDER: Michael Saxon REPLY: Frank Perreault If fuel is flowing to the carbs OK, then it indicates
something goofy at the carbs. Make sure the petcock is
in the Normal position first. Place a gas catch container
under the fuel bowl of carb #1 and remove the screw in the bottom of
the bowl. Place the petcock in Prime and you should see
fuel flowing into the catch container. If it doesn't then that
would indicate a blockage in the fuel line filter, the fuel line or
the fuel rail on the carbs. If it does flow correctly, then
that means the fuel system/carbs are fine and you probably have
electrical problems. So, I'm looking for other explanations. I'm beginning to suspect that the fancy Accel coils I installed are bad. I have checked and rechecked all of my connections. The crimps are good and tight, and all the wires and HT leads are securely attached. Normally, you'd be surprised to have two coils fail at almost the same time, but what if there was a manufacturing defect???? Any idea how I could test the coils off the bike? If they are
bad, I want to get a refund... One thing to try is to immediately unscrew one
sparkplug from the engine once the bike quits running, lay it on the
engine away from the sparkplug hole and try turning over the engine
to see if you get any spark. If you do, then you know the
electrics are fine and that you still have a fuel problem of some
sort. On the trip home, the rust migrated toward the petcock and
now it's in a position to do it a little quicker. That explains the
difference in the miles to shutdown. Ok, there are arguments against
this solution, but it's the best I've got. A check of the primary resistance of the Accel coils determined that the coils were labeled and packaged incorrectly - they are the .7 ohm CDI coils, not the 3 ohm transistorized ignition coils. Accel is replacing them under warranty. I think I'll sell them - the stock coils I bought for $25 are in great shape! DATE: July 20, 1998 I am sorting out those caliper axle's, just wondered if you could help with another question. When I had my engine re-ringed and liners the mechanic said he couldn't set up the carbs properly because the tip of one of the needle's had been snapped of and was jammed in its hole, also the carbs were showing there age lots of wear in them. Finding a set of carbs to replace them with is turning into a search for a needle in a haystack, all the ones seen so far are not much better. Have you any suggestions for replacement carbs, or would it be cheaper to have them re-furbished if it is possible. RIDER: Nick Tasker REPLY: Zack Schultz DATE: May 2, 1998 I took the bike for a test ride and it rode OK but it doesn't seem to keep a good idle. How would I adjust the idle to stay at 2000rpm's? This seems to be a good idle speed. Is there anything else I need to do to keep it running? More info... I just purchased a 1979 GS550 for $500. When I bought the bike the owner said that he had recently had work done to the carbs and had the rear brake overhauled. This was yesterday April 25th, but then today when I started the bike the oil pressure light flickers when the bike is at about 2,000 RPM's or below. There is also a clattering sound coming from the starter housing at this rpm level. The owner said that the idle may need adjusting to keep the bike at a level of 2,000 RPM's. My question is what do I do keep the bike at a constant level of idling? Could anyone make any suggestions????? As this is my first bike. Also could you offer any other suggestions as to what I should do to keep my bike running well. RIDER: Willie D. Smith REPLY: Frank Perreault Looking at this note closer doesn't give me a warm fuzzy
feeling though. The kicker here is that the oil light is
flickering at 2000RPM. This would indicate either it's low on
oil, the oil was never changed so it turned into molasses or the
bike has been stored for a long, long time. In either case, it
indicates neglect. But I'd investigate the oil pressure problem before you spend any $$ on the carbs. That's an ominous prob. I have had my light flicker on in isolated cases just after a sudden stop, but that was at 1100RPM idle, and then only for a few seconds. Assuming the oil and filter is fresh and the oil level is in the window, my suggestion is to drop the exhaust pipes and the sump plate at the bottom of the engine, and hope the pump's pickup screen is gunked up. This is actually listed as periodic maint. in my owner's manual, and I actually did it ...once. All that trouble and it was disappointedly clean. It's some hassle getting the pipes back on, and you need the sump gasket and the rings that seal the pipes at the head, but it's really more labor than actual financial expenditure. I would hope for a clogged screen, because I suspect the other options are much more expensive. Although I suppose it could be the sending unit for the light...otherwise the next step is to check the pressure at the oil gallery at the base of the cylinders... email me back if you want to get into that. Good luck. DATE: July 20, 1998 I have an '82 GS110E with about 5,000 miles on it. I have not ridden this bike in a long time but just got it up and running (very smooth). I left the bike in my garage for about 4 days and noticed a strong gasoline smell. I looked at the fuelcock and it was set to "pri". I adjusted the setting to "on" and the owner's manual states, " leaving the fuelcock in the "prime" position may cause the carburetors to overflow and fuel to run into the engine. it is possible that this may cause severe mechanical damage when the engine is started". Can anyone advise me ??? I thought I leave the bike alone for two days and then start it ?? RIDER: Dan Siegenfeld REPLY: Frank Perreault DATE: July 13, 1998 Last weekend my bike was thrown against a wall and laid over on it's left side. Now my bike won't start (unless pushed) absolutely nothing is happening when I push the ignition. Second, once I do get it running it wants to continue to idle at 3500, if I force the rpm's down (go into first gear) the idle will stay down until I grab the clutch. By the way, I didn't wreck. The bike was picked up and thrown (long story). RIDER: Robert A. Smedley REPLY: Zack Schultz I'd guess from your description that there has been damage to
the carbs or cables leading to them. Possibly the cable housing has
been crushed and the throttle cable is now sticking causing the high
idle. It's also possible that the float level has been modified by
this sudden contact with a solid object. In essence causing it to
run very rich (hard starting). Or, since you don't mention the
actual starting problem (doesn't crank etc.) that you've blown a
fuse or cut some wires. Or still yet, you've damaged the starter
clutch. I'm just guessing here, but if it's like my 1980 GS550E, then it's a small plastic button-like cover on the bottom of the handlebar bracket that the lever attaches to. The switch prevents you from engaging the starter w/o pulling in the clutch..but if the lever got bent in the, er...accident, then those contacts need adjustment. CAUTION: If yours are like the one on the '550, then it's a spring-loaded deal that will pop out if you remove the two screws, so just loosen them with a small Phillips screwdriver and slide them while someone else holds the brake on, and the clutch lever all the way in, together w/the starter button pressed. You'll hear the starter when you complete the circuit. This is assuming that the switch survived the ordeal...Otherwise you could just jump the switch where it plugs into the harness(in the headlight?), but then you lose the safety factor. I'm getting fuzzy reception from your description of the idle prob, but I'm guessing the throttle twist grip got hammered too, and it's not returning to idle by itself anymore. Loosen up the screws holding the twist-grip on, and see if it works better. If the grip got mushed, there's probably too much drag for the return spring to deal with at the carb end. Or maybe you need to adjust more slack in the throttle cable. Good Luck DATE: July 13, 1998 This is the second 550E I've owned. I loved my first, however the one I just bought is a fixer-upper. The four tubes that run from the carbs to the filter are missing, and the third carb leaks gas like a sieve. The bike won't go over 20mph and eventually floods. Is this something I can fix (as a novice) or should I take the bike to a dealer? Do you know the est. cost? Otherwise, it's all cosmetic. That I know I can fix, but I would love a good source for reasonably priced parts. Any suggestions? RIDER: Renee' Schmidt REPLY: Frank Perreault Seconds, it sounds like the carbs may need to be cleaned out. Unless you have a service manual and are mechanically inclined, you may just want to take it to the dealer to have it done. DATE: July 13, 1998 I recently bought an '81 GS450S. It starts and runs fine, but in the morning, after about 7-8 miles, the engine just dies. I have to run it with almost a full choke or it will die. I bought it from a local dealership, and they have been sort of helpful, but they have not been able to fix it. I have had the tank petcock replaced and have run a full tank of 93 octane through it. It seems to happen only when it is very humid. Thanks in advance, and your sight is excellent. RIDER: Chris West REPLY: Frank Perreault DATE: June 27, 1998 I have a 1978 GS1000E. It doesn't run too well. I've had squillions of dollars worth of work done on the motor and it still doesn't run very well. Specifically, when you throttle on you have to do it a bit slowly and carefully, otherwise the engine fades severely and only comes back to life with a arm wrenching jolt when you throttle off a bit. Is this flooding? I think my problems are partly due to the fact some clever soul did some shonky things under the cylinder head a few years back (don't ask me what, I forgot what the mechanic told me - doh!) and also partly due (I THINK) to the fact that I don't have a normal air box on it but instead have four of those dinky little pod air filters. A few mechanics have told me this is the root of all my problems. I don't really understand why - and would LOVE someone to explain it for me. Surely the pd filters just let more air in, if the fuel/air mix is adjusted correctly (and I assume it is considering how much I paid the mechanic) shouldn't the bike still run fine just a bit faster for given accelerator twist? Anyway I bought a second hand air box for the thing but the rubbers were too old and hard to fit the carbies. Even warmed in hot water, lubed with slippery spray stuff, slightly reamed with sandpaper (I was getting desperate) and with two of us wrestling with them on the garage floor. The actually have to be fitted in-situ but I figured if I couldn't get it right on the garage floor it was never going to work. Does anybody have some clever way of fitting these things? You cant buy new rubbers and all the second hand air boxes have these old rigid ones. I suspect that might be why someone fitted the pod filters in the first place. RIDER: Errol Hunt REPLY: Brian Underwood DATE: June 27, 1998 This is an excellent Q&A section! I recently had my 80 GS850GL carbs cleaned after a rebuild about two years ago. I have had the bike sitting for quite some time and after getting the carbs back, all four were leaking fuel out the airbox. I took the carbs back off, took them apart and found that the needles were stuck open. I tapped on them and they dropped into the seats. Should the floats have a little "spring" in them as they rest on the needles? One carb does but the others do not..curious. I need to get a new petcock diaphragm due to the other one is shot. Please help! RIDER: Kevin Blackstone REPLY: Frank Perreault DATE: June 27, 1998 I have an 1981 GS 750 with Mikuni CV carbs. I was (finally) able to get the carbs off the bike for a cleaning. The shop manual shows an oil seal (material unknown) and cover for the shaft that the butterfly valve (throttle valve?) rotates on. I'm not clear how to get the cover (it looks like a small metal cap) off the shaft end; it's not screwed on. All I want to do is to immerse the carbs is some cleaner. Do I need to remove the oil seal on the valve shaft? Will the carb cleaner eat away at the seal? If I do need to remove the oil seal, does anyone know how to remove the cover? My Clymer's manual doesn't specifically indicate that this oil seal needs to be removed, but it does say that all rubber and plastic parts should be removed prior to soaking in carb cleaner. Any help is appreciated. RIDER: Clay Ward REPLY: Bob Frisbie I like the spray can's ''cause you can stick the tube up the holes and blast out all the junk. My technique is to spray it in and scrub with a cloth or brush where possible. I believe that if you strip the carbs down and spray "em real good (2 or 3 cans per 4 carbs) you'll do just as well as a soak. DATE: June 27, 1998 Had a problem with my "83 GS1100E that I solved (finally), maybe it deserves posting. I listed it a long time back. The bike would idle fine, start right up with some choke, and run pretty good too. But, several times it just stopped on me, usually when I let off the throttle at 80 or so and always 20 miles from home. But sometimes it would stop at a light at idle. Downshifting and popping the clutch wouldn't do it. Sitting for 10 minutes would usually clear the problem, and, if I hadn't run my Wal-Mart battery down in frustration, I could cruise home. It seemed kind of intermittent as I couldn't make it stall. I thought it must be the auto petcock closing off from the loss of vacuum during deceleration. Or, maybe the fuel tank screen was filled with tiny bits of rust (I'd acidized the tank to clean it) Or, maybe my fuel filter was too small. Or the fuel line was somehow clogged. In any case, it seemed to me to be a gas problem. Well, it turned out to be the gas cap vent. I tried draining the tank through the petcock as a test, and after it flowed out a few cup of gas, the flow would slow, then stop completely. Eureka! Well, I took the cap apart and the interior was loaded with crud. I scrubbed it our with some gas and decided to hog out the vent holes just a bit. I put it back on and it still vacuum locked. Turned out to have some more corrosion between the top cap cover and the bottom, aluminum lock and vent assembly. A little shot of compressed air helped blow out some debris and, ba-da-boom - ba-da- bing, success! RIDER: Bob Frisbie DATE: June 27, 1998 I have a 1981 GS850 G. It had been in a storage shed for about 6 mos, through a 100*f.+ summer. It ran fine when I parked it. When I got it out and looked in the gas tank, I could see no crud and the gas smelled normal. I know I should have drained everything first, but I didn't. I had expected the battery to be dead after 6 mos. but when I turned on the switch and pushed the button, the damn thing started and off I went. Ran great for 2 days and then one day it started rough and gas was running out of the airbox. 1/2 a tank of gas was gone, later discovered it had run into the crankcase, oil was mostly gas. I drained out the oil and changed the filter, took the carbs off and had them cleaned, cleaned out the gas tank, probably not needed as everything looked pretty good. Installed new air box boots. It ran fine for a couple of days, then same problem. After parking it for a few days, gas starts dripping out the airbox covers., If I pull the covers off and reach with my finger into the back of the carbs and raise the plungers up and let them slide back down a couple of times, the gas quits leaking. Doesn't do it all the time, seems to run as good as ever, just went on a 300 mile trip with it and no problem other than just described. Also gas doesn't leak into oil pan when I park it on the side stand instead of the center stand What do you suggest? RIDER: Dave Porterfield REPLY: Frank Perreault If the petcock checks out OK, you may want to take the carbs
apart and check the floats for holes and check the float adjustments
on all the carbs. DATE: June 27, 1998 Is there another method to sync. the carbs. on my 81' GS650G other than using a Manometer? RIDER: Marty Palmer REPLY: Frank Perreault DATE: June 27, 1998 I recently bought an '81 GS450S. It starts and runs fine, but in the morning, after about 7-8 miles, the engine just dies. I have to run it with almost a full choke or it will die. I bought it from a local dealership, and they have been sort of helpful, but they have not been able to fix it. I have had the tank petcock replaced and have run a full tank of 93 octane through it. It seems to happen only when it is very humid. Thanks in advance, and your sight is excellent. RIDER: Chris West REPLY: Frank Perreault DATE: June 11, 1998 I have a 1981 GS1000GL with 22,000 KM's on it. I've owned it for 4 years, and am happy with it. Last summer I did some work, including battery, tires, paint, mufflers. Other than the fairly free-flowing mufflers, the bike is stock. Near the end of last season, the motor would die just before I came to a complete stop, when decelerating for stop signs. It didn't used to do this. I found the battery was cracked (never grind your old mufflers off with the battery in place), and planned to fix it in the spring. This year I brought it out of its heated storage. It didn't run well at all. Then I replaced the battery, spark plugs, and drained the fuel tank to replace it with fresh premium. The old plugs were fairly black and sooty, but as I mentioned I did run them a bit this year on the old gas from last season. Now it starts readily on full choke, misses a bit for the first 10 seconds or so (cylinder #3 I think), then runs well. Except it still wants to die when I'm coming to a stop. It fires right back up afterwards. I perform routine oil changes etc, but have no idea when the last valve adjustment was done (hesitant to do the shim type). What should a valve adjustment cost at a shop? Carb synchronizing? Thanks for any help. RIDER: John Ruttle REPLY: Frank Perreault DATE: June 11, 1998 I have a 83 GS1100E and I am trying to find the right jet size combination for my bike. Suzuki shop here in town says the stock ones are, pilot 45, main 125. I have a Yoshimura with K&N filters which should mean I should have to go up a size or so on both. No way, this thing is so rich with the #45 pilots you can see the raw fuel pouring out the exhaust. On the other end it seems that in order to get enough fuel on top end I have to run a #150. Anybody with some experience on this would be grateful. Thanks! RIDER: Ken Wagner REPLY: Pete Peters DATE: May 25, 1998 I read every Questions & Answer in the Fuel/Exhaust section tonight. There were a couple that sounded similar, but did not solve my problem. The problem is that the engine will only run when it is choked at least a little. Background: I just purchased my cycle from a friend who has had it in storage since 1995. There was 3/4 of a tank of gas still in it. I removed the tank, airbox (clean) & the carbs. I carefully stripped down and cleaned and reassembled each carb and found no plugged jets or and "old gas" residue. All 4 cylinders have spark and the engine does run fairly smooth when choked. The carbs are the constant velocity variety. I have mercury gauges to sync them when I can get the engine to run. Help. RIDER: Bill Gindt REPLY: Scott Horner I continued to search for other problems and discovered that the exhaust valves on cylinders 2 & 3 did not close/seat completely. I adjusted the cam gap and restarted the bike. The valves do close now, but they don't seat tightly. Time for a valve job. Thanks for the assist. DATE: May 17, 1998 Now that the engine will run idle, but very rough. It won't rev even a little unless I partially cover thus restricting air flow into carb #3. There seems to be equal suction on all 4 carbs (measured by placing my hand in front of the carbs). The engine can be revved only when restricting air flow into carb #3. All 4 carbs have been thoroughly cleaned by dunking. RIDER: Bill Gindt REPLY: Frank Perreault DATE: May 17, 1998 I read every Questions & Answer in the Fuel/Exhaust section tonight. There were a couple that sounded similar, but did not solve my problem. The problem is that the engine will only run when it is choked at least a little. Background: I just purchased my cycle from a friend who has had it in storage since 1995. There was 3/4 of a tank of gas still in it. I removed the tank, airbox (clean) & the carbs. I carefully stripped down and cleaned and reassembled each carb and found no plugged jets or and "old gas" residue. All 4 cylinders have spark and the engine does run fairly smooth when choked. The carbs are the constant velocity variety. I have mercury gauges to sync them when I can get the engine to run. Help. RIDER: Bill Gindt REPLY: Bill Gindt DATE: May 17, 1998 I have an '82 GS550MZ with a Vance&Hines header and 4 K&N filters. I increased the size of the main jets in the stock CV carbs, but it still seems a little weak in the top end. Do I need to start playing with the pilot jets, needle positions, something else? Any help with tuning would be appreciated. RIDER: Phil North REPLY: Zack Schultz DATE: May 17, 1997 I'm putting a dormant GS700E back on the road as soon as I can get the engine running. Bike has set for a year or two, no fuel getting to most cylinders, drain plugs on 3 and 4 carbs lets out stuff that smells like turpentine. Assume that I need to de-shellac carbs, but I can't get the assembly out of the bike!! Is there a secret to this? RIDER: Don Wallace REPLY: Frank Perreault Your wanting to take the carbs out to clean them
is a good move. Since the gas smells like turpentine, a simple carb
draining will probably not be enough to clean the carbs out (Though
it may be worth a shot!). You just want to make sure that you don't
mess anything up like the float adjustments in the course of
cleaning them out, hence, the recommendation to dig up a shop manual
if you can. I did this a few times. It is much easier for me to remove my
carbs now because I trashed the air box and replaced it with
individual filters. Now its a piece of cake to remove the carbs. The
bike has more acceleration now too! DATE: May 17, 1998 We have a GS650 sitting in the garage, which the number 3 cylinder does not appear to be getting fuel. There is spark, compression but we cannot figure out why there is no fuel going to #3. There does not appear to be anything wrong with the carbs. Can someone please help - it's getting/got to the point where we're stumped. RIDER: Michelle & Henk Zeeven REPLY: Zack Schultz DATE: May 2, 1998 I have an 81' GS1100E. Is it normal that I have gas in the oil because the petcock was left in the prime position for about 1 month? Does the float needle suppose to prevent this from happening or is it due to the prolonged period. If it is the cause why doesn't it happen on bikes that do not have a vacuum operated petcock. PS. this site is a miracle, great etc..... RIDER: Jacques Sakaitis REPLY: Frank Perreault DATE: May 2, 1998 I have an opportunity to buy this model. Everything looks okay, but the engine feels sluggish, like its missing under load. Ignition seems OK Any ideas greatly appreciated. RIDER: Glenn Taylor REPLY: Frank Perreault DATE: May 2, 1998 I am trying to replace the exhaust on my '81 GS 750 L. Both sides of the stock exhaust have large holes in them. Do you have any recommendation on a good 4 into 1 exhaust? What is involved in switching to a 4 into 1 system? RIDER: Kevin Dorrian REPLY: Frank Perreault As for types, look in this section to see what you can get. Racing exhausts like Super Trapp, Kerker, Yoshimura and Vance and Hines are some of the most well known. The switch will typically involve have to get a set of K&N filters for the carbs, removing and throwing away the stock airbox and putting the filters in its place. Finally, rejetting the carbs using a DynaJet kit will need to be done. DATE: May 2, 1998 Hi; History:
RIDER: Kevin Klevesahl REPLY: Frank Perreault There is a reason behind people using most aftermarket headers and it isn't because people are dying for good gas mileage. If gas mileage is your big concern, I'd suggest going back to a stock exhaust and standard jetting. The stock configuration will give you the best balance between power and fuel economy. As for shocks and suspension, check out the various articles in the Q&A - Suspension section. DATE: May 2, 1998 My bike is a 1982 GS750TZ and the situation is like this: the bike runs very good, it is easy to start and it idles very well. When riding, there is a shuddering and lack of power below 3,000 to 3,500 rpm's in 3rd to 5th gears. Twisting the throttle more than is usually necessary causes the bike to take off like a rocket. Also, there is no shuddering or lack power above those rpm's. The problem is that it seems to be running on only three cylinders. #2 is dead. When the bike is idling, the #2 exhaust pipe is warm at best while the others can boil spit. When I pull the spark plug, it is usually wet. There have been times when the cylinder was firing; I could tell this by the smoke that was coming from the exhaust at first (it seemed to be blue), and pulling the spark plug wire caused the rpm's to drop. Also the spark plug accumulates a black crusty deposit. Fuel consumption is double what it used to be--25 mpg compared to 51 mpg. I have:
My next guess is that the coils are weak, but I don't want to replace them without being more sure--I don't need to throw away a $100. This is everything I know and have done up till now, please HELP! RIDER: Gregg Wagner REPLY: Frank Perreault I got a chance to pull the carbs again and did find the problem. I had most of the #2 (and #1 for comparison) disassembled when the #2 low speed jet fell out of its home underneath it's little rubber plug--BINGO! I remember when I first cleaned the carbs 2 months ago, that one of the low speed jets had its screw driver slot messed up (by previous mechanic). I must not have gotten it back in all the way or something--maybe I even forgot to screw it in? I don't know. I usually have to work at a faster pace than I would prefer; when I am working on my bike, I am usually stealing or borrowing time from my parenting duties--not ideal time, but it's what I've got right now. Thanks again for your ideas and help. DATE: April 16, 1998 Upon re-assembling the carbs to the engine, I have two 6mm hoses running from either side of the fuel feed pipe. I cannot figure out where they should connect to and cannot remember where they were originally. They are between carbs 1&2 and 3&4. Can you help me with this if possible? RIDER: Tristan Shanahan REPLY: Frank Perreault DATE: April 16, 1998 In my Haynes manual, it indicates that the mufflers can be detached from the header pipes by loosening clamps and sliding the mufflers back and off. When I got the bike, the left side muffler was neither attached nor lined up at the point where a bolt holds it to the frame, and I wanted to move it to line up so I could firmly attach it. I found a clamp on the outer pipe and loosened it, but it seems like the inner pipe is directly welded to the muffler via a 2 into 1 manifold. Is there really a way to move the muffler independent of the pipes? RIDER: Ryan Biggs REPLY: Tim Noell DATE: April 16, 1998 I just bought a 1981 GS 450 LX, It starts and runs fine (a little noisy). After driving open road for 10 or 15 miles, the bike will want to stall a red lights and I have to rev up the rpm's to avoid a stall. Do I just need to adjust the idle, if so, how. By the way, I have been searching for a site like yours for some time. THIS IS GREAT! RIDER: Robert A. Smedley REPLY: Zack Schultz Check to make sure that the choke plungers are returning to the full closed position when you close the choke after start up. I've seen them get munged up on a lot of bikes and stay open a bit. DATE: April 16, 1998 I have a 1982 GS850GL. That has sitting for quite some time. My friend and I recently made an attempt to get it started. We had it running but throttle response was very poor and it was leaking gas out of the overflow tubes. We removed the carbs to clean them but all did not go well. We couldn't remove the diaphragm cover screws. so we couldn't clean them completely. So we did what we could and cleaned the main jets and ran compressed air through some of the passage ways. We bolted the carbs back on and assembled everything else. Went to hit the starter button and not even a sign of any gas in the cylinders. We tried again and again and apparently there was no gas going to the spark plugs. I find it difficult to believe that what we did is keeping all the cylinders from firing. Any response would be greatly appreciated. RIDER: Dave Goldstein REPLY: Frank Perreault DATE: April 16, 1998 I took the tank off of my '82 750EZ in order to repaint. I finished the beautiful paint job, and suddenly it seems as if there is a connection needing a hose, and the manual doesn't even list the part. There are two parts that attach to the underside of the tank. The first is the fuel cock, which I have reattached correctly. The other is the mysterious part that I hope you can tell me about. It has an electrical connection, which I have connected correctly (this leads me to believe that it might be the fuel gauge), and it also has a metal nipple that looks like it should be connected to something. For the life of me, I cannot figure out what this metal nipple is! It appears as though the fuel would simply drain out of this part, and I fear leaving it unattended. Any ideas? RIDER: Nick Green REPLY: Frank Perreault 1. Fuel Petcock (which has fuel line, vacuum hose, lever) 2. * Mysterious Part * (which has double electrical connection, unconnected metal nipple) This part is located on the same side as the fuel petcock, but is a separate part. Is this perhaps an air intake? DATE: April 10, 1998 I recently removed and Cleaned the carburetors on my 1981 GS750 that was stored to long. Removing the float bowls I cleaned all the passages I could get to without separating the carbs. After reinstalling the carbs and running the engine, It seem to idle correctly but small pools of fuel are collecting at the intakes and drips slowly into the air box. I was careful not to bend the float adjustments when cleaning. This GS only has 5000mi on it and ran great before it was stored. I appreciate any suggestions to this problem. Thanks. RIDER: Manny Iberra REPLY: Frank Perreault If you go with method #1 make sure that the bike is outside in open air and not in your basement or garage. DATE: March 22, 1998 I was wondering if anyone has the original horsepower and torque curves for this bike. I plan on getting the engine dyno tuned and am interested in how it compares to the original numbers. Also, has anyone had success with one particular pipe? I am thinking of replacing the stock pipes with either a Vance & Hines or Kerker megaphone. With proper jetting changes and K&N filters, is one pipe superior to the other? Thanks in advance. RIDER: Stephen Belle REPLY: Mike Saxon DATE: March 22, 1998 I have been reading the GS Resources for a year, which I have been also a owner of a slightly built -81 750 GSX. I am finishing my bike for a summer season, here in Finland it's something to wait for. When the bike is ready, I'm gonna send a picture to GS Resources, and hopefully it's going to be published. But meanwhile, as an experienced repairer, you could save my time and money having an answer to following: 32 mm carburetors have originally 112,5 jets; now I have changed the exhaust system for Motad and jets are too small. Which size most likely gives the best results. If you could please give your opinion? RIDER: Jani Mykkänen REPLY: Mike Saxon DATE: March 22, 1998 I have the parts on the way to rebuild the carbs on my 79GS1000L. I am going to try to rebuild them myself. I think this will be a good learning experience. Can you give me a brief outline on the project to steer me in the right direction? RIDER: Rick Langevin REPLY: Frank Perreault DATE: February 15, 1998 I have a GS850 from '78 and it runs fine but... Starting the
machine when the engine is cold takes a couple of minutes. RIDER: Arthur REPLY: Zack Schultz DATE: March 8, 1998 I have the cold start problem that has appeared in some other questions here. Will having the carbs rejetted help and be worth the trouble? RIDER: Greg Traxler REPLY: Frank Perreault DATE: February 15, 1998 I saw your response to a jetting/carb/pipe question in the GS
Resources, and wanted your opinion on something. RIDER: Robb Zimdars REPLY: Zack Schultz DATE: February 15, 1998 I have a 1982 GS1100EZ with a stock set of 34mm Mikuni CV carbs with a Dynajet kit. My questions are 1) Would these carbs fit on a 1978 GS750 and 2) would a set of 40mm Mikuni CV carbs from a 1995 Canadian model GSX-R1100 fit the 1982 GS1100 and what performance benefits would this have? (I would install a Dynajet kit on these too) RIDER: D. Rogers REPLY: Zack Schultz DATE: February 15, 1998 I was looking through some of the older GS resources answers, and saw a question similar to mine. The rider in question found (after the fact) that he wasn't supposed to adjust or even turn (Clymer's words) the fuel jet screw located on the bottom of his Mikuni carbs. You described to him how to adjust the mixture needles, but I don't think that is what he was looking for. My situation is similar -- I purchased a 1979 GS750E that had been sitting for far too long, the carbs were totally fouled (slides would not move) and had to be "dunked" which requires the removal of even the fuel jet screw. I have the Clymer manual, and in the performance section, they recommend a jetting change and an associated fuel jet screw setting. I followed their suggestions and now the three cylinders that are firing run very well (I suspect one more clogged passage). My Question: Is there any literature available concerning the Mikuni carbs? I check all of my local sources and come up dry. The Clymer manual has been a help, but it would be very helpful to have a description of what each passage and needle does. RIDER: LINKOUS@aol.com REPLY: Zack Schultz DATE: February 15, 1998 Hi! I came across your homepage and decided to ask you a few
questions. I am from Singapore and I am currently riding a
GSXR400K. Just got it 2 weeks ago. When I first got the
bike it is able to move but then after I send it to a carb cleaning
service I found out that the fourth carb's needle is broken.
Since now all the needle is replaced and the slides too. I still
can't figure out the problem why the engine always dies off.
It can never settle down to idle running. RIDER: Johnny REPLY: Frank Perreault DATE: January 15, 1998 The number 1 spark plug on my 1981 GS650GL indicates that that cylinder is running rich (the whole thing is covered in dry, black, sooty deposits). The bike has less than 7000 miles on it and the carbs where replaced a couple of years ago. It is not an ignition problem and I was wondering if anyone could tell me what to look for when I take apart the #1 carb. RIDER: Joe Smith REPLY: Frank Perreault DATE: December 5, 1997 I just started a winter cleanup project on
my newly acquired 1978 Suzuki GS 750. I pulled and drained the tank
and the gas that came out was very dirty and rusty. The end of the
siphon hose had some crud on it. I called a local radiator shop. The
guy there told me he couldn't clean the tank, but could line it for
about $35. He said "the rustier, the better" for the
process he uses. RIDER: Bill REPLY: Frank Perreault DATE: December 5, 1997 Am curious about re-chroming the exhaust pipes on my GS1100G. They don't seem to be badly pitted but are a bit crusty looking. Is it practicable, or should I just belly up to the bar and buy new? Uhhh --- if available. RIDER: Ken Barton REPLY: Frank Perreault DATE: December 5, 1997 I'm putting a dormant GS700E back on the road as soon as I can get the engine running. Bike has set for a year or two, no fuel getting to most cylinders, drain plugs on 3 and 4 carbs lets out stuff that smells like turpentine. Assume that I need to de-shellac carbs, but I can't get the assembly out of the bike!! Is there a secret to this? RIDER: Don Wallace REPLY: Frank Perreault DATE: November 8, 1997 This is a request on behalf of a friend who owns a mis-match of a
GS1000. RIDER: Neil John Gallacher REPLY: Peter Huppertz DATE: November 8, 1997 I own an 82 GS850L- recently, I installed a Vance & Hines chrome megaphone pipe to replace the old 4-2 which had rusted pretty well out. I also installed a K&N replacement air filter. Now I've got a flat spot right around 4K. I was going to have the carbs cleaned (probably need it) and rejetted, but the guy I was going to said that my best bet was with a carb jet kit...the only place that I could find one was DynoJet and that's a stage III kit...I don't want to lose the stock airbox. Anyhow, anybody done this before, so they can make a recommendation? Anybody know of a good bike shop in the Baltimore area? HELP! RIDER: John Kazmierczak REPLY: Frank Perreault DATE: November 4, 1997 Frank, I came across your name in the GS RESOURCES QUESTIONS AND ANSWERS section. Seeing that you have answered a lot of questions I figured that I would give you a try with a problem that I have with my 1979 GS1000L. I purchased the bike 2 years ago for almost nothing. (Saddest looking thing I ever seen, parts missing, seized engine, etc.) Anyway I got the motor unseized and after removing the carbs about a dozen times I finally got the bike running. Once I had it running , it gave me more hope so I stripped the bike down to the bare frame and began to restore it. The bike really looks great. Anyway, back to my problem. The last time I removed the carbs I went over them with a fine tooth comb making sure every hole was open (finding a lot of them plugged). Not having a service manual at the time, I removed the mixture screws at the base of the carbs near the float bowls. After getting my manual I realized that these screws are factory set and should not have been tampered with. I haven't got a clue in the world what they should be set at. Asked around and got nowhere. By the way the carbs are Mikuni, the VM type. Hope you can help me out. P.S. Would a synchronization test help in this adjustment. RIDER: Joey Van De Ligt REPLY: Frank Perreault If the bike will start, go for a ride and warm the beast up. You don't want to be running the choke when setting idle mixtures. So, to get the idle mixture screws initially set, turn all four screws clockwise until they seat lightly. And I do mean lightly! If you go too tight you'll ruin the needle seat or the needle itself and then you'll really have problems. You might also want to keep track of how many turns you made on each screw, just in case my method doesn't work for your carb. It should but you never know... Once you have it seated lightly, then turn the screws counter-clockwise 1 1/4 to 1 1/2 turns. This will get you into the ballpark but with the sync tool you could then adjust the screw slightly in order to see if you could adjust it better. If the bike wouldn't start before, give it a shot now and get the bike hot. It should start. Shut it off and hook up the sync tool to each carb. Of course, you'll need to run the bike with the tank off the bike, so you'll need a rig to get gas to the carbs. Restart the bike and tweak the mixture screw in both directions by no more than a 1/2 a turn to see if you can more vacuum, i.e. the mercury rises more in the sync tool. Leave the screw set so that the mercury is at the high point and do this for all four carbs. Once all the carbs are done, you will now need to balance out all four carbs with one another using the sync tool. The adjustments on the carbs for making this adjustment should be in your service manual. This is how I typically handle idle screws. Good luck and congrats on the restoration project! Send a picture when you're done, to editors at the GS Resources and we'll see if we can get you name in lights. DATE: Dec 8, 1996 I have a GS 1100 E with the Vance and Hines Super Sport header. The pipe is in good condition but it is showing its age. I have painted it numerous times to keep it looking good but I still have to paint it once or twice a season. I have found out that it cannot be black chromed as the pipes are too close together and the electroplating arcs between the pipes during the process ruining the job. I was also told that powder coating will not stand up to the heat and the temperature differences. Is there something out there that I can us to clean up the pipes? I don't mind painting, but it does have to last. Any info would be appreciated. RIDER: Doug Berry REPLY: Bill Chandler DATE: Oct 3, 1996 I Have a 77 Suzuki 750. I am replacing the gas line. It's been a while since I took it off, so I don't know how to put it back. How does it go? RIDER: ZACK1201@aol.com REPLY: Frank Perreault DATE: Aug 30, 1996 I have a 1981 GS850 with 9,000 original miles. I can feel the carbs backfire at low RPM's. The Plastic sidecovers shake and a dull popping noise is heard. I can feel the backfire if touching the intake manifold on the left side of the bike. I just spent $500.00 to have the carbs rebuilt and synced at Suzuki. Is this backfire dangerous to the bike? What causes it. I tightened all bolts thinking it was an air leak, What's a GS 850 L worth? RIDER: Mark Anthon REPLY: Bill Chandler DATE: Aug 28, 1996 I recently purchased a 1981 GS450T that was based in Minnesota. I live in Colorado Springs at 6000 + ft. elevation. The bike starts fine at first, but after running a few minutes, I have difficulty keeping it running at low idle. If it stalls, it's almost impossible to restart. Seems like it's starving for gas, because even with holding the throttle wide open during attempts to restart it just lugs along. Do you think I have a clogged fuel system, or do I need to have the carbs adjusted or re-jetted? RIDER: Skip REPLY: Frank Perreault DATE: Aug 25, 1996 I have a 1982 GS 1100 G. It had been sitting in a garage for 2 years and am having trouble getting it to stay running. At first it would not start at all. I put a new battery in, new air filter and drained the tank and put new fuel in. Today it started and idled for a few minutes and stopped. I pulled the plugs and found carbon build up; cleaned them, put back in and it started reluctantly, and idled unevenly, and then it stops. Any suggestions on where to go from here? RIDER: RC REPLY: Frank Perreault DATE: July 23, 1996 I have a 1980 GS750 that was left out in the rain and snow. I have spent a year working on it and still have a problem with gas leaking into the crankcase. I have replaced the vacuum actuated fuel petcock, rebuilt the carbs, adjusted the floats, and replace one leaking seat valve. This is really starting to bug me. Any advice would be appreciated. Also is there a way to convert to a manual petcock? Thanks in advance. RIDER: Tom Holt REPLY: Frank Perreault DATE: July 13, 1996 I own a 1988 GSX600 (katana), The exhaust pipe is emitting flames, but only when I exceed 50miles per hour, Does anyone know the reason for this? thank you, (ed.) I know Jose's bike does not fall into our "CLASSIC" series, but maybe someone could help him out on this. RIDER: Jose Luis A. Mariz Molinari REPLY: Peter Huppertz DATE: July 3, 1996 I have A Suzuki GS1100es '83. I have bored my bike with a WISECO
1168 kit. It equates to 105 thousands of an inch oversize. The stock
jets are 112. I need to get an up-size. I have installed K&N
filters. RIDER: Ian Harris REPLY: Frank Perreault DATE: January 20, 1996 I bought this bike two years ago with 3300 miles on it. It has always been garaged and came equipped with the original tires. It looks like new but did not run great as you can imagine after only being used a few miles each year. I had the carbs cleaned with only marginal improvement. Finally, I drilled out the air/mixture plugs and readjusted the carbs with great success. Immediately after adjustment, it ran better and all of the plugs cleared up from carbon black to gray/brownish the way the should look, except for the number 2 plug, the one with the idle adjustment on it. This one continues to look black and no further adjustment improves the situation. IF ANYONE HAS ANY SUGGESTIONS ON HOW TO CORRECT THIS, I WOULD APPRECIATE THE HELP. RIDER: Barry G. Davis REPLIES: Bill Chandler |
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