So close...

[Topman]

Alright, I'll start by saying how new I am at working on bikes, and how enjoyable it has been thus far.

I purchased my '81 GS750L from a friend of a friend who just wasn't show it any love, he hadn't ridden it in well over a year, and neglected it on every front. Fortunately he had only owned it for 2 years and the owner before him had taken great care of her.

I got it knowing there was problems with the charging system, so that's where I started. I managed to get it running with the old oil and gas in it. Just shot it with some starter fluid and ran up/down the driveway a couple times and she cranked right over and ran like a champ. I started my testing on the charging system with the help of The Stator Papers, and quickly came to the conclusion that both the Stator and the R/R had been fried. I took the advice of this website and replaced them both with Electrosport Industries parts (a move I'm becoming more weary of as I read more posts regarding their R/R). I didn't take out the whole wiring harness, but I used CRC's electronic cleaner and went to town on all the ends. After taking the engine side covers off, I decided to polish them up, clean the Carbs as much as I could without taking them apart (they seemed to be in pretty good shape), replace the screws with bolts, and of course get her new spark plugs. While I had her jacked up I then also replaced the tires/tubes, break pads, and break fluid. The rear caliper is going to need some work, the pistons won't budge an inch, but I decided I wanted to get her running before I even bothered with that. So I mounted the gas tank, and battery, refilled the oil and fuel, and cranked her up, with no luck. She sounds like she wants to start, cranked and even sputtered some but didn't go. I hit her with starter fluid for a couple go rounds and did in fact get her running, for quite a while to check everything out. Had some fuel leaking, but I narrowed that down, and came to the conclusion it was because the rubber in between the carbs had dried up and was leaking, after shutting her off and waiting a while I went back and didn't have any leaks; assumed the rubber had gotten the fuel it needed to moisten up and expand again. By then it was dark and I didn't want to disturb all my neighbors by cranking a very loud motorcycle when it wasn't entirely necessary, so I slept on it. Went to work, and came back this afternoon to see if she'd be a trooper and start up for me. The battery had a good charge, checked out at 12.83 before turning the key, good start. Turned the key, cranked her, but got no start. Even tried hitting it with starter fluid for old time's sake, but she'd just rev up then sputter down and die, and I refuse to keep relying on starter fluid, so I'd really like to figure this one out.

Me being in a bit of a money crunch, I'm looking for a decently cheap and not so time consuming approach to solving this. So given zero advice, my next plan of action was going to be to remove the wiring harness and thoroughly clean all the odds and ends, looking at the same time for anywhere that may have been burned or damaged in any way, but I decided I'd confide in the brain trust that is the GSResources forums first.

I truly appreciate any advice or random thoughts on the subject.

 

[BassCliff]

Hi,

You received your "mega-welcome" in THIS THREAD. I'm totally serious about the maintenance lists included in said "mega-welcome". Almost every item is absolutely critical. If you want your motorcycle to run reliably and safely, there are no "silver bullet", cheap, quick fixes. You have a 30 year old machine that has been abused and neglected. It needs proper maintenance. Any shortcuts will leave you frustrated.


Thank you for your indulgence,

BassCliff

 

[Indysteve]

Ok, lets start with some real easy tests

Remove your spark plugs and insert them into their boots.
Lay them on the cylinder head and crank the engine over for a short time.
Check your spark, and this is real easy in the dark.
A nice blue spark is what you are after.
You want to turn the engine over for no more than 8-10 seconds.
The second thing about doing this in the dark is that if there are any shorts in the electrical system they should show as a spark where you did not want one.

Now test your coils. Measure the resistance and verify they are within spec.

Check your voltage at the coils, this will help to make sure your cleaning had the desired affect.

You said you just replaced the carb screws but nothing else, correct?
Did you drop the bowls at all?
Most of the time you can drop the bowl and it will tell you a story about what shape the carbs are in.
Dirty bowl, slime in the bottom, buildup on the floats all mean that the old fuel had a negative impact on your carburetors.

This will also help verify whether you have fuel feed problems.

You said the boots seemed hard to you, I would never expect a boot to come back from 'hard', and a lean condition is not good for an engine as it has a tendency to burn things up.

An engine takes three ingredients in the right proportion to run correctly:
1.) Fuel
2.) Air
3.) Spark

If any are off it will most likely run but not well.
If there is a lack of any, then the engine will not run.

You stated that starting fluid HAD worked but did not work any longer.
Where were you spraying the starting fluid?
If you sprayed into the open carbs you were introducing a much higher combustible fuel into a lean condition which can and will damage your valves and or pistons if done over an extended period of time, so please use sparingly.

I would check spark, check fuel and if you want to try 'priming' put a SMALL amount of fuel directly into the cylinder, we used to use an oil can and a SMALL squirt, then replace the spark plug and try to fire it.
If it runs for any length of time then you most likely have a fuel issue.

Good luck and report back:!:

 

[Fizzyhair]

I'll second that list. Mine was like a different bike just for doing the clearances and cleaning out the carbs. It vets addictive though on e you see the benefits you can't stop doing every little thing possible lol

 

[tom203]

" got it knowing there was problems with the charging system, so that's where I started. I managed to get it running with the old oil and gas in it. Just shot it with some starter fluid and ran up/down the driveway a couple times and she cranked right over and ran like a champ"

So before you did any work on it, it "ran like a champ" on the old gas (after starter fluid help) ? Sounds like old fuel in bowls is gone now and new stuff ain't finding the way to the carbs. NO fuel- NO start! Throw away starter fluid and spend some time at Basscliff's and read up on likely culprits- take advantage of the advice and avoid needless frustration. Avoid buying parts till you're sure you need them.

 

[SVSooke]

The people here seem to harp on a proper carb cleaning and new O rings http://www.cycleorings.com/.There is a reason.I got away with doing a quick but complete disassembly job on my Old Yeller(see sig thread) project bike.IT ran OK.Did complete tear down plus a dip and Mr Barr's O rings.Now it runs like new!Carbs look scary but if you use the resources of GSR and BassCliff you can do it.There really are no shortcuts on doing it so do it once and then you can enjoy your bike.

 

[Topman]

Hey all, thanks for the replies.


Just got in from work, and it's quite late, not to mention dark here. I did manage to get out and at least test the sparks. In the dark, I got a great spark show, they all seem to be firing just fine, and no unexpected sparks elsewhere. I plan on getting in some of the other tests you mentioned before work tomorrow, but I wanted to get a head start tonight to make the most of my limited time. And that brings me to my next problem, can't seem to find instructions on testing the voltage or resistance on the coils. The fantastic portion on 'ignition coil testing' in my Clymer manual says simply "the easiest way to test a coil is to swap it with a known working one" which does me no good whatsoever. Also couldn't find any specs for my bike during that hunt either, so if anyone knows any general standards might help.


I didn't replace the carb screws, nor did I drop them. Prior to the PO this bike was owned by a guy who took meticulous care of it, it was then sold to a friend of my buddy. Judging by visual inspection, it's clear the carbs were taken off seperated and cleaned at some point, he even went to the hassle of polishing each one individually, so I doubt if he put them together with the same O-rings and/or gaskets. On top of that, although this bike was not well maintained by the PO, I know my buddy hated seeing this bike not being used, and I know for a fact he was on top of his friend about at very least stabilizing his fuel before it sat for any long period of time.
The cleaning I did involved just carb cleaner on the body of the carbs, to remove residual build up, nothing internal. I double checked tonight, there's no feed problems I can see. I removed one of the screws and fuel came pouring out.


The boot issue you're referring to IndySteve is something I just assumed. I read on one forum that if the carbs sit for a little while without fuel in them, that the boots can dry up a bit and perhaps lose mass. When I first had everything back together and couldn't get her to start up, I got her started with starter fluid, at that time fuel had only been in the carbs for a few minutes after having sat dry for nearly a month. I had her running for several minutes before I noticed fuel leaking from somewhere on the carbs, so I shut her off, removed the tank, and thoroughly wiped down the carbs. I then ran her again to try and locate where the fuel leak was coming from, but alas on the second run, it didn't leak a drop, so my assumption was that on the first run, the boots hadn't absorbed all the gasoline they could handle and were thus not completely tight and sealed, hence the leaking. But after taking the time to stop the bike, remove the tank, and clean up, they had perhaps swollen back to their moist size and were no longer leaking. Just to clarify I never actually felt the boots' stiffness.


After just getting the bike put back together I did get her to start after a couple shots of starter fluid, but the following day I chose not to be so trigger happy with the fluid. After shooting her once and not getting the success I had established the day before, I decided not to shoot her again, and instead figure out why she couldn't start on her own, so it's not that the starter fluid stopped working. When I did use the starter fluid though, I sprayed it into the open airbox, so not directly into the carbs, but pretty darn close.


For tomorrow I plan on trying the priming method mentioned, just have to find a dropper to control how much gasoline I apply.


Thanks again for all your help.

 

[SVSooke]

Ah the tales noobs will tell.Your carbs may be fine and done.Untill you take them off and tear them down you will not know how they are.Avoding the issue will not change the fact that you need to at least look!
Editr take the advice of my friend in the post below

 

[cowboyup3371]

Clean the carbs!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[GS1100GK]

So many things...all good advice.

If it were I, I would pull the fuel line off the tank (not the carb side as it is PITA to put back on without removing the carbs), turn the petcock to PRIME and run a little fuel into a clear container to check color, smell, and for any rust or other debris.

Replace fuel line and let it sit with petcock on prime for a few minutes to fill the carb bowls. (Note: Prime bypasses the vacuum requirement) Then try to start with choke.

If it doesn't start in about 20 secs, stop and check the voltage (with a voltmeter) on the incoming line of the coils. Then check it while cranking. It MUST stay above 10.5, preferably > 11.5 If it drops below, the coils won't fire reliably.

These bikes don't like an unregulated air supply. Make sure the boots, air filter box and filter are in place and closed up when trying to start.

This is quick and dirty and not intended to be complete or to negate any of the necessary items suggested already. It is an effort to get you some fire from your bike.

 

[dueller]

+2 to cleaning carbs

+2 to cleaning carbs

I bout a GS700EF last summer. Had to start it with starting fluid frequently. Parked it for the winter. Went to go and get it going again this season. Wouldn't start. Hit it with starting fluid and would run.....but only as long as there was the shot of starting fluid. So I decided no time like the present to no longer put off the rebuild. Rebuilt the carbs for the cost of the dip ($20) and the intake boot kit and oring kit from Mr. Barr. (Think that total was like $47)
When you mentioned you fuel leak, you said it was the rubber hoses between the carbs. You're talking about the little like 1" ones right? I have two differnent tubes on my rack of carbs (I am not familiar with your setup but I think it is similiar). I have a rubber one that is just for the venting of fuel/fumes. There is another one that is aluminum (I think) and has o-rings on each end of it where it goes into the carb body (these are some of the o-rings that are included in the kit you will get from Mr. Barr). These are the fuel supply hoses. Those SHOULD carry fuel. If your setup is the same as mine and you have fuel leaking from the runner ones. THAT AINT GOOD! That would mean that your needle valves aren't shutting off the fuel supply from the tank and are overflowing your carb bowls. If this is the case, check your oil to make sure you don't have gas in it. Long story short (I know too late) I rebuilt my carbs and haven't looked back. Bike runs now without start fluid every time! Put some 4K miles on her in the last couple months Daily rider. Also, when you mention "boots" in relation to carbs most people are talking about your intake boots which are the 30some mm passages that connect the carbs to the head. If you look on cycle-orings the stainless bolt kit is where this is used.

I did come across a couple threads that mention the coil resistance test you mention. Just do some searching and you will find. I will post back if I happen to come across them again.

 

[Topman]

Thanks for that bit, I appreciate how humane your response was dueller. I had planned on taking everyone's advice to clean the carbs, ordered the O-rings from that awsome site recommended, as well as some some dip off ebay. I decided to go out anyways and futz with the bike before work. Put all the spark caps back on just for the sake of it, pulled the fuel line and emptied some into a container, turned out to be clean and fresh. I put the hose back on and put it on PRI for a bit (as recommended). Chose to stop when I noticed it had begun to overflow into my airbox. Cleaned that up as best I could, and decided to give her a crank.... She started right up, no choke or anything. I was amazed. I even then started working on the rear caliper which wasn't getting any brake fluid previously, was going to remove it and disassemble it to clean, suddenly got it working too. I'm not sure what happened over night, but everything was working for me today. I'm going to keep an eye on her, and wait until I have a few days of successful starts before I try and take her out on the road.

One thing I was tinkering with before stopping for the day was the clutch, I've adjusted it up and down completely but it seems no matter what I do, it is always very loose. Is there something I may have missed doing, having just put the right engine cover back on in the last week?

 

[Steve]

I was going to offer some suggestions, ... until I saw this:

The cleaning I did involved just carb cleaner on the body of the carbs, to remove residual build up, nothing internal. I double checked tonight, there's no feed problems I can see. I removed one of the screws and fuel came pouring out.

You know, it doesn't really matter how grungy the carbs look on the outside.

All of the gas is supposed to flow on the INSIDE.

If it's not clean there, it won't matter.

Your problem is not getting the gas TO the carbs, it's trying to get it THROUGH them.


A couple of points you will come to learn:
1. All previous owners are liars. They are selling the bike for a reason, so will tell you stuff that will help sell the bike.
2. Don't trust what they told you. Again, they are all liars.
3. Don't assume that, because he took "meticulous care" of the bike (probably just the body work), that he know what to do to maintain the bike.

Go though the welcome page on BassCliff's site, you probably got it already. There is stuff in there that HAS to be done. I would even go through the list if I got a NEW bike, it's that important. Add in the fact that you are dealing with a 30-year-old machine, it makes it that much more important.

Clean the carbs properly, then we'll talk.

.

 

[GS1100GK]

I put the hose back on and put it on PRI for a bit (as recommended). Chose to stop when I noticed it had begun to overflow into my airbox.

If the fuel was running into your airbox, most likely one or more floats are sticking. This could also be the cause of the leaking carbs in the beginning.

Your carbs should not be overflowing.

This is a sign your carbs likely need a good thorough cleaning. It is some work and there is a learning curve. Printing out the guide on Bass Cliff's site is a great help and I recommend taking pics of your throttle and choke linkages while on the bike and at various stages of disassembly to aide in reassembly.

That's the bad news.

The good news is you've proven it will run and the carb situation is a big part of your troubles. It's good because it is within your power to fix rather easily.

Personally, I prefer to have a bike 'running' (no matter how poorly) before tearing something major apart. It makes troubleshooting and 'tuning up' easier.

The fuel issues you are having will haunt your bike and can leave you stranded until you fix them. It's a new bike for you.

May as well knock that out and be done with it. It has to be done and the sooner you do it, the more hair you'll have left

 

[dueller]

You know, it doesn't really matter how grungy the carbs look on the outside.

All of the gas is supposed to flow on the INSIDE.

If it's not clean there, it won't matter.

Your problem is not getting the gas TO the carbs, it's trying to get it THROUGH them.

Exaclty!!

A couple of points you will come to learn:
1. All previous owners are liars. They are selling the bike for a reason, so will tell you stuff that will help sell the bike.
2. Don't trust what they told you. Again, they are all liars.

Well MOST sellers are liars. Some bald face and some lying by omission The previous owner that I bought my bike from said that he rode his back and forth to work on nice days. Now either he was truthful and my luck just struck like normal cuz I didn't get it home and hit the dreaded charging system issues or he was lying. I am more inclined to think that it was my luck cuz I rode it like 50 miles and had no trouble even after I cam back a few hours later and it started right up, but who can say....

 

[dueller]

Forgot to say......you might wanna check your oil or maybe just change it! If you had gas running into your airbox, it could very likely have overflowed into your intake ports and drained past the piston rungs into your crankcase. At the very least open your fill cap and smell in there. If it smells like gas change! Not a bad idea to just change it anyways. Only be like $15. Not bad insurance.

 

[dueller]

So? Been able to make any headway on it?

 

[Topman]

You bet. Dueller you were absolutely correct about the fuel in my oil, thank you for that. I realized the error in my ways. I was getting way too excited to get out on the open road.. Everyone's comments have brought me back to reality. I'm taking the carbs off, gonna dip them as soon as all the goodies get here in the mail. Waiting on a feeler gauge to adjust the valve clearances. Just replaced the clutch springs today, thinking I may need to replace the clutch cable because I still can't seem to get it as tight as I'd like. Got new sprockets, waiting on a new chain (old one is definitely on the brink) as well as new muffler connectors (noticed an obvious leak coming from there). Also cleaned the rear caliper yesterday, it was pretty nasty so I took the rear M/C apart today, something I should have done anyways when I noticed fluid leaking from a tiny hole in the boot.
Which brings me to another issue, inside the piston bore there is a minor build up of something almost like rust or just gunk too stuck on to get off with q-tips or a tooth brush (mediocre picture attached), is this going to be a problem? I didn't notice any gouges or scrapes otherwise. If the piston and cup set look to be in good shape, is it feasible to just replace the seals and boot?
When it comes to cleaning the carbs... Robert Barr's instructions included with my new O-ring set states that you should not dip float bowls 1 & 2 because they have a plastic liner that the dip will destroy, how then should I go about cleaning them thoroughly? Along with the new O-rings, after cleaning, I have a carb sync tool to do just that, also have a caliper to assist in adjusting the float bowl per the guide, what other measures have I over looked in terms of prepping them to perform their best?

 

[dueller]

Which brings me to another issue, inside the piston bore there is a minor build up of something almost like rust or just gunk too stuck on to get off with q-tips or a tooth brush (mediocre picture attached), is this going to be a problem? I didn't notice any gouges or scrapes otherwise. If the piston and cup set look to be in good shape, is it feasible to just replace the seals and boot?

Glad I could help on the gas in the oil. Seen it suggested to another poster. Absolutely. If all the hard parts look good give it a try. There's a rebuild doc on Basscliff's site. I have to do mine badly! I'm not sure what your pic is. That's inside the bore of the caliper? or inside the piston? You'd probably be ok. If you have to maybe use a little bit of fine steel wool so you don't cause deep gouges just finish the surface.

When it comes to cleaning the carbs... Robert Barr's instructions included with my new O-ring set states that you should not dip float bowls 1 & 2 because they have a plastic liner that the dip will destroy, how then should I go about cleaning them thoroughly? Along with the new O-rings, after cleaning, I have a carb sync tool to do just that, also have a caliper to assist in adjusting the float bowl per the guide, what other measures have I over looked in terms of prepping them to perform their best?

I dipped mine. Of course there was some slight oxidation after being exposed to the elements after a few days. I am hoping to take them off this winter and clean up the outsides and paint them up. Check out JWhelan65's rebuild thread. I think it's in the middle somewhere. Had his painted up and I am planning on following that paint scheme but blue in the spots where he used black.

 

[dueller]

Any luck? How's the carbs comin?