Gas in exaust

[Anonymous]

ok, i think i figured out why i'm using so much gas, i had a bit of rich exaust this weekend, and thought it was just a mixture issue.... so today i decided to try to drop down one size on my jets just for experimental purposes, I noticed that at a small break in the weld where the exaust connects under the bike that it was dripping raw fuel... So how is my fuel getting all the way there without burning. Is it maybe a plug and plug wire issue, plugs got pretty nasty, there shiney black, i'm kind of lost and stumped again. can somebody tell me why gas would be getting down there.

[Anonymous]

anybody? hehe please? hehe pretty please? hehe

[dgeorge]

Hi Joe, the only thing that I can think of is it is running extremly rich and pushing raw fuel out the exhaust valve. Now as to why it is running rich is another problem, which could be any number or combination of things. Give the guys with more experiance some time to see if they can come up with anything.

[Anonymous]

Both exhausts or just the left hand side one? Mine would occasionally drip gas into the #1 cylinder when parked on the sidestand. Sounds like float valves not sealing.

[fastpakr]

True, but to get it into the exhaust would require it being pumped through the exhaust valve. I don't see how this could be as simple as an overflowing bowl?

[bwringer]

You didn't say which bike is having the problem, but if it's the GS850, it's quite possible that the petcock diaphragm has gone bad. This would suck large quantities of fuel through the vacuum port on the #2 carb, and from there it could easily make its way into the engine, etc. The other GS might have the same setup, but I don't know.

The classic symptom of a bad petcock is a crankcase full of fuel after sitting overnight. However, if it's a very tiny leak, it could only leak noticably when its under vacuum. In that case, you'll see the #2 plug foul while the rest are OK.


In any case, I wouldn't run the bike until it's sorted. The raw gas can't be doing the rings and cylinders any good, and the gas is bound to make its way down to the crankcase. Give your oil a sniff -- bet it's got gas in it.

[Anonymous]

Are you absolutely sure that the stuff you found is pure gasoline and not condensed water, which often happens in exhaust pipes?

[Anonymous]

Check your petcock like bwringer said.

My '81 650 was gassing out my girlfriend when she was riding behind me and it was the petcock.

Basically the petcock diapragm had a hole in it and the #2 cylinder was pulling fuel directly into the cylinder and it was pouring out the left hand exhaust. If you kneeled down behind the bike at idle you would almost pass out from the pure gas vapors.

Anyway, a new petcock on eBay for 42.00 and all was well.

[Anonymous]

cool deal, exactly my buddies that were riding behind me this weekend said that they could really smell the gas, guess its a good thing the ups man brought my new petcock today i've been using an old tank so that might just be my problem. guess i need to change the oil again as well in the morning i'll put my right tank on there with my new pengal and see what happens maybe that is all it is, that tank is super old and the petcock my just be fubared on it, it is my 850 btw, seems like the only bike i have problems with, my 750 with the tscc has never missed a beat other than the burnt clutch from the cloud of smoke i gave a smart arse harely guy that said my bike wouldn't even turn the tire over , it is stock to the bone, my gs has a few mods, i wish i would have left it alone......... but i think when i get the minors sorted out it will all be good , oh yea and i bet your right about the petcock cause it is the left pipe that gas is coming out of thank you much for shareing your experience. I've found this website is absolutely the greatest thing that has happend to me, i'm really looking forward to meeting some of you a month and a half now woot getting close guys

[prism4]

Fuel In Oil

I just changed the oil and found a lot of fuel in the crankcase. ? I was told that the petcock may not be working correctly. I took the plugs out and found the number 2 plug to be wet. Could it be that the petcock is leaking fuel into the vaccum? I disconnected the vaccum line and it dripped a few drops of gas?? Is this ok?? PLease help. I do not have a lot of bike experience. Thanks

[Tarbash 27]

are sure that cylinder that is leaking the gas is even firing. its sounds to me like you could be running on 3 cylinders and that one cylinder is just pumping out fuel.

[moto_dan]

Re: Fuel In Oil

I just changed the oil and found a lot of fuel in the crankcase. ? I was told that the petcock may not be working correctly. I took the plugs out and found the number 2 plug to be wet. Could it be that the petcock is leaking fuel into the vaccum? I disconnected the vaccum line and it dripped a few drops of gas?? Is this ok?? PLease help. I do not have a lot of bike experience. Thanks

Sure signs of a bad diaphram in you petcock.

[prism4]

well i took the tank off and the petcock and i am goin to try and rebuild it. If tat does not stop the "Gas in the tank issue" what would be the next step?? Thanks

[ccratin]

That's most likely your issue. Make sure you put in a fresh plug and then check it again later to see how it's burning. Also, at idle that cylinder is likely not firing, so the exhaust won't be hot once the bike warms up. Check wtih a water spray on the exhaust. It should burn off almost instantaneously if it's running properly.

The only other potential issue is the float valve in the carburetor not seating properly. Generally that won't cause you to have that much gas in the exhaust, but it can cause gas in the oil if the carb overflows through the intake into the cylinder. However, if that cylinder isn't running because of fouling, that'll get gas into your oil too.

[moto_dan]

well i took the tank off and the petcock and i am goin to try and rebuild it. If tat does not stop the "Gas in the tank issue" what would be the next step?? Thanks

There shouldn't be a next step if you get a good rebuild on your fuel valve(petcock), but the next step would be to check your needle seat valve(s) in your carbs.
Pay close attention when you disassembly the petcock. There is a small semicircular stainless steel spring that is easily distorted during the process that is responsible for pushing on the diaphram when you position the petcock in "P"prime position manually overiding the auto shut off feature. On sure way to correct the problem is to replace the vacuum operated valve(petcock) with a Pingel, manually operated one.