'81 GS750E Won't start

[meeks7]

I have spent several hours searching and reading here and I have figured out that I screwed up firstly by not getting this thing running good before we started making changes. We bought this bike a good while ago for my son to learn to ride on. It has 50k miles on it, when I took it for a test ride it seemed to run good but was a little down on power I thought. That was OK with me since my son is 15 and just learning to ride, we could rebuild it later on if he decided to keep it. It had a wobble in the front end which I think was a combination of steering stem bearings and a leaking fork. The forks were rebuilt, I replaced the steering stem bearings and the wheel bearings also.

I jumped ahead of myself, let me back up. Before we did the above things, I was letting him ride it in a large parking lot close to our house. It did alright for a few days and then didn't run so well. The exhaust had a hole in it where it had been drug on something. My son didn't like the looks of the stock exhaust anyway so we bought a VH 4-1 system for it. At the same time we bought a DynoJet Stage 3 kit as suggested by VH and also bought a set of inexpensive pod filters off eBay.

When installing the DJ kit, I had trouble with the mixture screws and you all helped me figure out what to do with that, thanks for the help. Some things came up and the bike sat for awhile before we got back to it. When I had the carbs off I cleaned everything out really well and installed everything per the instructions in the DJ kit. We put new plugs in it and reinstalled the carbs. Now I can't get it to run at all. If I use starting fluid it will start and run shortly, but won't take any throttle. If you keep twisting the throttle, it will run for about a minute before dying. It doesn't make any difference what you do with the choke. That's another issue, I guess I cleaned things too well and now the choke won't stay applied when you pull the cable. It slides so easy that it just falls back to the open position. Guess that's what I get for being so picky with the cleaning.

I don't know where to start to get this taken care of. Any help with a list of what to check and what order to do it in would be greatly appreciated. I don't want to take it to a dealer because I know most of the stuff I will be able to do myself plus I already have too much money in this thing anyway. I am almost to the point of going and buying him a new bike and parting this one out to recoup some of my money. If anyone would be so kind as to give me some direction to go with this I would really appreciate it. Thanks in advance for any help you all can give.

Stacy

 

[Guest]

Try priming the float bowls with the prime function on the petcock.

 

[Nessism]

Look on the choke cable to see if there is a friction adjuster to keep if from closing after you pull it open. And relax, there is no such thing as cleaning things too well.

From the way you describe the problem the engine is starved for fuel. Make sure you have the fuel line and vacuum line from the tank hooked up properly. Also, make sure the petcock is functioning properly; turn the lever to prime and make sure fuel flows and then suck on the vacuum line and see that fuel flows. You want to use the prime position to fill the float bowls prior to starting after the float bowls are drained.

If in doubt about fuel in the carbs, loosen the drains to see if there is fuel in the float bowls. If not, start troubleshooting starting with the line and petcock.

Good luck.

 

[TheRedlineMan]

When you cleaned the carbs did you replace the fuel lines? If you did then make sure the new lines aren't any longer than the originals. longer fuel lines will crimp and starve the carbs for fuel when the tank is put in place.

 

[nabrams]

Now hold on a minute here - Has it ever run with those pod filters?????
If not, you DO know that putting pods on totally changes the jetting story, right????
Now, if I were you, I'd toss those pods in the trash and put that stock airbox and filter back on and enjoy the bike. Jetting pods is a total nightmare for the non-expert. See the MANY posts on this topic.

 

[spyug]

As mentioned, I think you have a fuel starvation problem. Kinked fuel supply hose is a likely culprit but to sort it all out start at the tank and petcock.

If the bike has been sitting around a while it is vey likely the tank is rusty and or the old gas had turned to sludge and glomed up the petcock. With the tank on the bike disconnect the hose at the pcock and replace with a hose run into a jelly jar. Turn the lever to prime and you should get a health flow. If the flow is weak or just a trickle, I'd pull the petcock for cleaning and rebuild.

If the flow is good then it could be kinked hose to the carb. Also if there is an inline filter between the pcock and carbs check to see a) if its old and clogged and b) if it is installed correctly. There is likely a direction of flow arrow printed on it.

I am not an expert on these bikes but it seems that they can be difficult to get running on pod filters. I know with my bike, after cleaning and rebuilding the carbs, it would not run without the airbox installed so you might try putting that back on.

The other thing I do know from my built up of the XS650 is that the cheap Emgo type pods are not at all restrictive and cause a super lean condition and hard starting. You can alleviate this abit by partially wrapping the outside of the pod with electrical tape so the open area of the mesh is 50% or less of the surface area. Better would be a switch to foam Unipod type.

One other thing to mention. It is not a good idea to use starter fluid or anything other than gas to start a bike. A shot too much and you can blow the head. You can put a bit of gas in a spritzer pump type bottle and squirt a bit in after opening the butterflies. Becareful as you can get a backfire through the carbs which could cause a problem i.e fire. I had a Virago with carbs that had the intakes point upward through a cut out in the frame ( where the airfilter was mounted). After a rebuild I was trying to start it with a drop of gas in each. A few cranks and nothing and as I'm looking in the carb throats "Kaboom" a big gout of flame shoots out and takes off my eyebrows !

Check the fuel circuit first.

Good luck and let us know what you find.

Cheers,
Spyug

 

[twistedwankel]

When I ride my FL 81-750 every 3rd day I can start it with an 1/8th turn of the throttle. A couple minutes and it's ready to go here in FL.

When I ride it once a week I have to use the choke full to start it. If your choke doesn't hold it's time to bypass the clutch cutoff switch so you can hold it open with the left hand. One guy put some thread gripper on the cable to get it to grab...try that.

When I let it sit for more than a week I have to Prime it first as apparently all the gas must evaporate out of the tiny bowls? Seems like it runs on two cylinders for a few seconds before it responds to throttle with all 4?

Such is life. My bike is perfectly stock and runs very well at 29k. I don't plan on ever changing anything from stock for that reason. I won't ride in the rain either.

Mind you - I live in FL now. When I lived in CT 60F cold starting was always with full choke and let run for 5-10 minutes before it had enough heat in it to idle without stalling. Once it had been run it would start without the choke and only an 1/8th twist.

 

[meeks7]

Here's what I have found so far, the first problem is no fuel to the carbs. I did as you all said and started there. The first trouble that I have is that there isn't a position labeled prime on the petcock. All I have is fuel and reserve. I am learning about Suzuki's so maybe I am missing something? I removed a couple of the float bowl drain screws and got nothing. I pulled the fuel line from the tank and checked for fuel by turning the petcock both ways-nothing. I removed the tank to empty it and remove the petcock to check it. The gas still smelled ok, but there was quite a bit of dirt in the tank, but the tank appears clean inside. The screen on the petcock was clean. I took the petcock apart and the only problem I found was the metal plate on the diaphragm is broken. About 1/4 of the top of it was broken off and laying inside the cover. The lower half appears to be on it's way to breaking also. It looks like it has been bending when it would work maybe. I am getting a small tank tomorrow that I can set up and gravity feed fuel to try while I decide what to do with the tank. I will find out if it runs when I hook the tank up and then report back. Thanks for all the replys and keep them coming.

 

[spyug]

Good to hear you are on track. Sounds like the petcock is pooched. I'd replace it. I'm not sure if OEM p'cocks are still available but I'd check with your local Zuk dealer first.

If the OEm part is not available you should be able to get a manual (not vacuum operated) from most parts retailers (Dennis Kirk\, Bikebandit etc) for $20 or less.

Hard to get the carbs to work if the gas isn't making it to them.

The remote reservoir is a great idea and if you can get it running on it then you are half ways home.

While you have the tank off and once you sort the p'cock change the hoses and likely you'll be sorted.

Keep at it and give us the good news when your running.

Cheers,
Spyug.

PS the other thing to do is get some Seafoam additive and add a few ounces to a fresh tank of gas. Gas if it sits for any length of time ( even a few weeks) will start to break down and will turn to varnish which will gum up carb jets. It will clean tjhings up and will keep the gas stable as it sits.It is also good for cleaning valves and you can use it in the engine oil to clean out oil passages. Great stuff.

 

[meeks7]

It's ALIVE!!!

It's ALIVE!!!

With a remote tank I have been able to get the bike to start and run. It won't idle on its own, but it will run with some throttle input. I have ordered a manual petcock that should be here in a couple of days. I know I have some work to do with carb adjustments to get it right. It doesn't rev very quickly, but it will accelerate. I need to read the papers that came with the DynoJet kit and read the information on here about tuning the carbs and see if I can get that sorted out. I need to get a cap for the vacuum line that went to the petcock and I think I will replace the fuel line from the tank to the carbs also. Should I cap the hose that goes from the vent on top of the head that went to the airbox or put some sort of filter on it?

I am sure that the valves need adjusted, but I want to get it running correctly before I do anything else that could cause a problem. What else should I be looking at doing to get this lined out? I have a nagging feeling that I am missing something simple that would make this all easier.

One thing that I noticed that someone might be able to shed some light on, the tach is very slow in reacting. As I said, the engine isn't real responsive, but the tach is even slower than the engine. If I remember correctly, when we first got the bike it reacted like a tach normally does. The only thing that I did to it was to clean and lube the tach cable. I used a light coating of wheel bearing grease when I reinstalled the cable, could this be causing it to work slowly or is it likely something in the tach itself?

Thanks to all of you for your help so far and please keep the info coming I really appreciate you all taking the time to help me out. :grin:

 

[nabrams]

That's great that you got her started, but the battle is just beginning.
The slow rev-up could vey likely be due to pods. You will tear your hair out from frustration trying get the carbs jetted right for pods (for all RPM ranges).
Besides that, there's a whole check-list of verifications you need to go through so that you're not playing endless guessing games about why things are not working. See the MANY posts by me and others regarding this list.

 

[paco13]

Do not plug the vent on top of the valve cover, get a push on filter vent. I used one with a male input so I could run a length of hose (Like the stock one) and mount the filter back further.
Plug/cap the vacuum port on #2 carb if not using vac operated Petcock and make sure you check for vac leaks at the intake boots before starting to jet. Float height fuel level important to before jetting, stock setting should be good just make sure the needle/seats are sealing good. Check the 2 carb vents are clear, Many people just remove the hose's. Sync the carbs.

 

[spyug]

I am sure that the valves need adjusted, but I want to get it running correctly before I do anything else that could cause a problem.

Actually, you should sort the valves before you delve into the carbs. I know this sounds wack but it is the correct order for tuning. If your valve clearances are out, you will never get the carbs set correctly.

Also, as mentioned, trying to set up carbs with a dyno jet kit and pods is going to be a real taxing experience. There are quite a few threads on this.

I think you should simplfy. Try to get a good running engine with stock components. Set the valve clearances, revert the carbs to stock jets, get fresh o-rings for your intake manifolds, get you're stock airbox on with a clean filter, fix your fuel flow. You'll need a manometer to synch your carbs (air/fuel mixture screw) so try and beg borrow or steal (or buy) one. Follow your manual and you will get it to run right...I'm sure.

It can definitely be frustrating getting the bike to run but you need to do it in steps and you really can't skip any (like the vlaves) if you want to do it effectively.

Keep at it and let us know what transpires next.

Keeping my fingers crossed for you.

spyug.

 

[meeks7]

Finally back at this thing

Finally back at this thing

After back surgery, I am finally able to get back to work on this bike. Here's what I have so far, to update those who have been helping me. As suggested, I adjusted the valves. What a difference! The intakes were slightly on the tight side and the exhausts were definitely tight. I adjusted them all to the loose side of spec since I know they will tighten up as we ride it. I didn't think to check the compression before adjusting the valves. After the valve adjustment, the compression is 135-140 across all 4 cylinders. With the valves adjusted, it starts right up whether it is cold or hot, but it seemed to be running rich all through the rpm range. Here is where I get back into trouble.

I was able to do a lot of reading while trying to heal from the surgery. One thing I noticed that I didn't do while I had the carbs apart before, was to check the float height, so I decided to do that thinking it could cause the rich condition. While I had the carbs off I also decided to drop the needle one position. This was something I had run into before on a dirt bike way back in the day. When I checked the float height, something just didn't seem right. When checking the float as everything I have read says to, using the lower part of the stepped float and inside the lip on the gasket surface, all of the floats were low. They all measured at .75" at the lower part of the float. If I went to the higher part of the float, where the float arm is, the measurement was .88". That's what didn't seem right since the manual and all the information I read here says to measure at the lower part of the float. I bent all of the float tabs to get the lower portion of the float to .88". It took a sizeable adjustment to get it there. Now the bike won't start. I'm assuming the float level is now too low when installed and not allowing enough fuel into the bowls. My next move is to take the carbs back off and put the float height back where it was since it ran with them the other way. I thought I would ask you all for any ideas/suggestions about the float height and what you thought about dropping the needle like I did. I appreciate everyone's help and will keep you updated as this unfolds more.

 

[BassCliff]

Hi Mr. meeks7,

It's good to hear you are back on your feet after surgery. I wish you a speedy and complete recovery. Check my website for the float height information I've gathered. There are also manuals for some GS bikes, carbs, and other stuff. It seems I may have been remiss with my duties so I am including my mega-welcome! \\/

Let it be known that on this day you are cordially and formally welcomed to the GSR Forum as a Junior Member in good standing with all the rights and privileges thereof. Further let it be known that your good standing can be improved with pictures (not you, your bike)![FONT=Arial, sans-serif] [/FONT]

Perhaps you've already seen these, but I like to remind all the new members. In addition to the carb rebuild series, I recommend visiting the In The Garage section via the GSR Homepage and check out the Stator Papers. There's also a lot of great information in the Old Q&A section. I have some documentation on my little BikeCliff website to help get you familiar with doing routine maintenance tasks (note that it is 850G-specific but many tasks are common to all GS bikes). Other "user contributed" informational sites include those of Mr. bwringer, Mr. tfb and Mr. robertbarr. And if your bike uses shims for valve adjustments, send an email to Mr. Steve requesting a copy of his Excel spreadsheet that helps you keep track of clearances, shim sizes and other service work.

These are some edited quotes from one of our dear beloved gurus, Mr. bwringer, with ideas on basic needs (depending on initial condition), parts, and accessories.
***********Quoted from Mr. bwringer************
Carburetor maintenance:

Replace the intake boot o-rings, and possibly the intake boots. Here's the procedure:
http://bwringer.com/gs/intakeorings.html
Here's an overview of what happens with this particular problem:
http://cycleorings.com/intake.html
You'll also want to examine the boots between the carbs and the airbox. There's a good chance these are OK, but check them over.
And finally, if things still aren't exactly right, you'll want to order a set of o-rings for BS carbs from the GS owner's best friend, Robert Barr:
http://cycleorings.com
Once you receive these rare rings of delight, then you'll want to thoroughly clean and rebuild your carburetors. Here are step-by-step instructions that make this simple:
http://thegsresources.com/gs_carbrebuild.htm
***********************************
Every GS850 has (or had) a set of well-known issues that MUST be addressed before you have a solid baseline for further troubleshooting. It's a vintage bike, and it's quite common (as in, every single GS850 I have had contact with) that there are multiple problems that have crept up and slowly gotten worse over the years. It's not like a newer vehicle, where there's generally one problem at a time.

These common issues are:

1. Intake O-rings (install NEW OEM or Viton only - common nitrile O-rings will quickly deteriorate from heat)
2. Intake Boots (install NEW -- these cannot be repaired)
3. Valve clearances (more important than most people think)
4. Carb/airbox boots
5. Airbox sealing
6. Air filter sealing
7. Petcock (install a NEW one)
8. On '79 models, install new points or Dyna electronic ignition (or at least verify that the old points are working correctly)
9. On all models, it's fairly common to have problems with the spark plug caps. These are $3 or $4 each, and often worth replacing if you're keeping the stock coils/wires.
10. Stock exhaust with NO leaks or holes -- good seals at the head and at the junctions underneath.
***************************************
OEM Parts/Online Fiches:

I would definitely double and triple the recommendations to use Cycle Recycle II and Z1 Enterprises as much as possible. These guys are priceless resources. Z1 tends to have slightly better prices, CRC2 has a wider range of goodies available. If you're near Indy and can bring in an old part to match, CRC2 has a vast inventory of used parts.
http://denniskirk.com - Put in your bike model and see what they have.
http://oldbikebarn.com - seems to be slowly regaining a decent reputation, but it's still caveat emptor. They don't have anything you can't get elsewhere at a better price anyway.
http://www.babbittsonline.com/ - Decent parts prices. Spendy shipping. Don't give you part numbers at all. Useful cross-reference if you obtain a part number elsewhere. Efficient service.
http://bikebandit.com - Fastest. Middlin' prices. Uses their own parts numbering system to obfuscate price comparisons -- can be very confusing for large orders. Cheapest shipping, so total cost usually isn't too bad.
http://flatoutmotorcycles.com - Slow. Cheapest parts prices, crazy shipping costs. Don't expect progress updates or much communication. Real Suzuki part numbers.
http://alpha-sports.com - Exorbitant parts prices. Different type of fiche interface that's quite useful at times, especially with superceded part numbers. Real parts numbers. Shipping cost and speed unknown due to insane, unholy pricing.

Stainless Bolts, Viton o-rings, metric taps, dies, assorted hard-to-find supplies and materials, etc:

http://mcmaster.com - Fast, cheap shipping, good prices. No order minimum, but many items like bolts come in packs of 25 or 50. Excellent resource.
http://motorcycleseatcovers.com - Great quality, perfect fit (on original seat foam), and available for pretty much every bike ever made. Avoid the textured vinyl -- it's perforated.
http://newenough.com - You DO have riding gear, don't you? Great clearances, always outstanding prices and impeccable service.
***************End Quote**********************
Additional parts/info links:

GSR Forum member Mr. duaneage has great used upgraded Honda regulator/rectifiers for our bikes. Send him a PM.
New electrical parts:
http://stores.ebay.com/RMSTATOR or http://www.rmstator.com/
http://www.ricksmotorsportelectrics.com/index.php
http://www.electrosport.com/
For valve cover and breather cover gaskets, I recommend Real Gaskets (reusable silicon):
http://www.realgaskets.com
The Rice Paddy (salvage/used)
http://www.ricepaddymotorcycles.com
Carolina Cycle
http://www.carolinacycle.com
Ron Ayers Motorsports
http://www.ronayers.com
MR Cycles
http://www.mrcycles.com
Moto Grid
http://www.motogrid.com
If all else fails, try this:
http://www.used-motorcycle-parts.org/
Used bike buying checklists:
http://www.amadirectlink.com/roadride/Riderresc/checklist.asp
http://www.clarity.net/~adam/buying-bike.html
Lots of good info/pictures here:
http://www.suzukicycles.org
http://www.cyclechaos.com/wiki/Motorcycle_Wiki

Thanks for joining us. Keep us informed of your progress. There's lots of good folk with good experience here.

Thank you for your indulgence,

BassCliff
(The unofficial GSR greeter)

 

[meeks7]

BassCliff, thanks for the welcome. I have checked out your website and found a lot of useable information. That is where I found the information about checking the float height and how to measure it. I checked in my manual also and found the same information. When I adjusted the float the way it shows, now it won't start. I'm waiting to see if someone chimes in with anything else to look into before pulling it apart again and resetting the floats. I'm not sure exactly where to set them since the thing won't run now. Thanks for the help.

 

[Griffin]

Stock float heights go out the window with different different jetting and pods. Set them back to where they were before. At least it ran, even if a bit rich.

Is it running rich at all throttle positions? You really should do plug chop tests at 1/4, 1/2, and wide open throttle positions to see what each circuit is running at.

My '81 750 was running very lean when I acquired it last year with a stock exhaust and air filter. I cleaned the carbs and set float heights per the manual, to no avail. I installed a DJ stage 1 kit, and raised float heights 0.1" above manual spec, and it runs great at all throttle positions now. Still maybe a tad lean at WOT, but since I'm never there for more than a few seconds, I don't really care.

Do the plug chops once you reset the float heights and see what you get.

 

[meeks7]

Well, now I am confused. I went out to the garage awhile ago for something other than the bike. While I was out there I decided to try starting it just to see what would happen. I had put the battery tender back on it overnight after trying to start it yesterday. I cranked it and it tried to start. Pulled the enrichener and hit the starter again and it fired right up. Didn't want to idle at first, but after 45-60 seconds started idling fine when I kicked the enrichener off. Let it warm up a few minutes at idle and then hit the throttle. The first couple of times it stumbled. Off idle it stumbled, from about 2k hit it and it stumbled. Did this a few times and decided that I still had issues to deal with. Let it sit and idle a couple more minutes while I did something else and decided to rev it a couple more times before I shut it off and went back in the house. It revved immediately and cleanly. Tried it off idle, worked great. Tried it from about 2k, awesome. I think I just need to get some issues with the lights ironed out and ride it for awhile and see what happens. If anyone has any suggestions or comments feel free to let them fly. I need to do some searching on here for info on plug chops as that is something new to me. I know how they do them with stock cars, but have never done it with a bike. Thanks to everyone who has offered any info and hopefully my ordeal might make someone elses life a little easier later.:-D