Getting grey hairs...............

[frosty5011]

2nd chance I've had this spring to ride the bike, and it almost leaves me stranded. Need advice.

The bike is 1980 GS850L, just finished the spring maintenance (oil change, had carbs synced, valve clearance checked, brake lines/calipers cleaned). Today, went for a ride (finally beautiful weather)....rode about 20 miles, then bike suddenly only started running on 3 cylinders.

Was not too far away from home, so thought I'd just continue on and check problem out at home. Drove about another 5 miles, another cylinder went out......could barely make 30 mph. Hit a hill and bike died going uphill on me.

While on side of road, I felt the pipes......felt like #1 and #4 had gone out. I pulled them (luckily I do carry some tools with me.... ), and they looked OK (#1 was kind of questionable.......the metal threaded socket is a mirror black, but the porcelain is almost snow white?.....whereas #4 looked perfect). Having had a spare plug, I switched out the #1 plug. I went to start the bike.....started with difficulty, did not want to stay on....had to "rev like hell" for a few seconds, then wife and I hopped on (yeah, she was with me), and off we went. Bit rough at first, but seemed to ride OK until I got home (another 5-8 miles or so).

What in the world could that have been about? The ignition coil that runs 1 and 4?....don't think so, otherwise it wouldn't have started again, right? Or can they somehow 'overheat' and run OK after cooling off?

Carb problem? When problem happened, it was over whole range. It did not change at all if I put it down in 2nd gear or so and tried to ride at high rpm's.....and did same at low rpm's. Unless I'm mistaken, I don't think it was dirty carbs.

Some kind of venting problem?......I didn't see that any vent hose was pinched or anything when I took seat off to get to tools, but then I didn't think to look then either. And if pinched, I don't think I would have gotten 20 miles or so without problems. Maybe cap vent???? What would be the best way to test this.....as stated, I already rode about 5 miles after the problem occured, without any incident.

I do have fuel filter....yes, it does have some rust flakes in it, but doesn't look like enough to clog the fuel flow through it. Will replace that anyways as soon as I get a new one.

I've got the stupid little petcock with only the screwdriver slot in it....could it mabye be something there, or the screen in the tank....don't really want to take that off yet, in case I ruin the gasket. I'm not sure yet I can get the gasket alone.....think I have to buy the whole re-build kit.

Any assistance would be highly appreciated.

[TheNose]

I had the same type symptons once. I unscrewed the plug out of the carb bowls and all the carbs were empty. I changed my fuel filter and it has worked ever since. Let us know what you find.

Terry

[frosty5011]

Nose,

After reading your post, and thinking about it......I wouldn't be surprised if my #1 and #4 float bowls were also empty. Since I have the vacuum-operated petcock, it would take about 10-20 seconds of engine turning over before they would fill........which is about how long it took when I went to restart it, before it would stay running.

But trying to figure out (if this was the case) what would cause the fuel starvation. I don't think it is clogged filter.....looks clean enough (although I know that I have fine rust in tank). Will change out filter first opportunity I get, but won't be able to get one before weekend at the earliest. My fuel hose to the filter looks a little kinked.....that probably happened at shop when they synched carbs. But, would it have run that far if the kink was bad enough to cause starvation?

[daveo]

also I've had the petcock diaphragm, that opens and closes by vacuum, get lodged semi closed by the spring locator inside breaking off and wedging, definitely sounds like fuel starvation, check that the gas cap is venting also

[Anonymous]

Nose,

After reading your post, and thinking about it......I wouldn't be surprised if my #1 and #4 float bowls were also empty. Since I have the vacuum-operated petcock, it would take about 10-20 seconds of engine turning over before they would fill........which is about how long it took when I went to restart it, before it would stay running.

But trying to figure out (if this was the case) what would cause the fuel starvation. I don't think it is clogged filter.....looks clean enough (although I know that I have fine rust in tank). Will change out filter first opportunity I get, but won't be able to get one before weekend at the earliest. My fuel hose to the filter looks a little kinked.....that probably happened at shop when they synched carbs. But, would it have run that far if the kink was bad enough to cause starvation?

We kinked the tank vent hose once and we thought the carbs were bad.

[lhanscom]

I managed to kink my fuel hose, and rode 15mi or so before it started acting up.

[frosty5011]

Looking more and more like either fuel / vent hose problem, or possibly cap not venting correctly. By the way, what is a good way to check the cap......to see if it is venting correctly?

And also.........just wish to thank those of you helping out here. It really does make life with a GS much more endurable when you know you've got a bunch of great people at the forum to fall back on when you run into a jam.

[Anonymous]

Looking more and more like either fuel / vent hose problem, or possibly cap not venting correctly. By the way, what is a good way to check the cap......to see if it is venting correctly?

And also.........just wish to thank those of you helping out here. It really does make life with a GS much more endurable when you know you've got a bunch of great people at the forum to fall back on when you run into a jam.

Leave it loose

[frosty5011]

Scotty says:

Leave it loose

Just scared I'll lose the thing that way.......... My tank has the detached cap, not connected by any hinge to the tank. Trying to re-create same circumstances as before, to see if any different, would mean drive about 20 miles with thing just lying loose in hole.

You gotta remember, I'm driving on Alabama country roads......just think how many Texas-sized potholes I run over in 20 miles......that thing would just pop right out

Guess I could drain tank a little, and drive without cap on at all.......

[lhanscom]

You could also wait for the symtoms to happen, then pop the cap open and see if it solves the problem.

[frosty5011]

Luke,

Wish I could do that, but read in other places where this might be caused by other things (such as rust flakes covering screen in tank, etc.) and that those problems would probably disappear once I shut off bike.

In order to open cap, I would have to stop bike, remove key from ignition and open cap with key. (Guess I should have another key made - thanks for reminding me). :?

Don't know if I made myself clear there, but I think you'll know what I mean. By the way......although I don't think at matters in this case.....bike is completely stock.....no special jetting, stock exhaust, stock airbox, etc.

[KEITH KRAUSE]

Gas cap vent.

I cleaned mine the other day.('79 GS1000) I used a small screwdriver to hold the key hole open and sprayed some carb cleaner in it.(watch your eyes)Quite a bit of dark brown spray came out. I could hear the little vent ball rattle when I shook it. If you ride the bike,especially a warmer day,pull over and turn bike off. Put your ear near the cap and you should hear the air venting. If you do it is still a good idea to clean it because it could be partially clogged and still vent some. KK.
PS: Is your petcock vacuum line in good condition? Any small cracks could open up as the bike gets hotter,reducing vacuum. With less fuel flowing into the carbs feeder passage,#2&3 carbs could 'hog' all the fuel?

[Anonymous]

Have you checked your plug caps? They fail with age and cause misfiring. You should get 5,000 ohms between the screw that does into the wire and the plug connector.

I had similar symptoms to you that went from intermittent to permanent, changed the caps, and the bike loved life from that moment.

Kim

[Anonymous]

Anyway, if you are getting gray hairs, as in the thread title, that's good news. It means you will soon be old enough to go riding around on an old GS. :-)

Kim

[Dink]

Frosty,
when you get that second key cut stick it in the tank cap and go for a runto see if youi can replicate the problem, now to check if it is a venting problem reach down and open the cap, if that helps you just found the problem.
Dink