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Page last modified: 09/03/08 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. |
