gas in the exhaust

[george.361]

Here is what I'm up against any thoughts?

I am having a hard time getting my 1981 GS 650 L to fire up with out several cranks. Once it does fuel comes out of the exhaust and continues to come out as the bike idles. All cyclinders are firing but it runs very rough and has a hard time holding a steady idle. I have checked the plugs and all the plugs look good and get a nice blue spark. After running the bike for some time to warm up and observe the leaking fuel, I removed all the plugs and found them all to good nice and dry except one cylinder. I know this cylinder is firing because it is hot but the plug is wet. I'm getting the fuel leak in the exhaust on this side of the bike so I'm under the assumption this is the the problematic area. What is causing this? I'm thinking either I need to do a timing adjustment and or a valve adjustment. I have made adjustment with the air screw on the carb which have seemed to make little difference. How far out until it unscrewing the air screw is useless? I also know the correct jets are being used as I just did a carb rebuild and check all the jets. Also shouldn't all the air screws be with in the relative vicinity of one another.....I find it hard to believe that all other fuel mixtures are spot on at 1.5 turns out and to have one completely different then the others.

[waterman]

I would bet that your trouble is either a faulty petcock leaking down the vacuum line to cylinder #2 (from left to right) or your carbs need some attention. The float on the cylinder that is leaking is flooding and allowing liquid gasoline to spill into combustion chamber and out exhaust. I question if the wet plugged cylinder is actually firing. Start with why carbs are dumping fuel, then worry about adjusting pilot screws. Also check oil for gas contamination, with gas coming out of exhaust it is likely getting into crankcase.

[Nessism]

I agree, carb and/or petcock related. Easy fix usually. Go through the carbs and don't skip an steps. http://www.thegsresources.com/gs_carbrebuild.htm

Check the petcock by installing a long piece of clear tubing on the vacuum input, and another piece of tubing on the gas outlet feeding into a gas can. Suck a vacuum on the clear vacuum line and gas should flow out of the outlet when the lever is in ON and RES. Also, no fuel down the vacuum line. When in the PRI position, the petcock should flow gas all the time.

Good luck.

[george.361]

Now that you mention the vacuum line I think you are right. When I had the tank of the bike I did notice that there was some fuel leaking out of the area for the hose connection, I thought it seemed funny but didn't give it much thought at the time. I will look into it and see what I find since it is the #2 plug that is wet. Thanks for the insight.

[catbed]

are you sure it is fuel? does it continue when the bike is warmed up? the mufflers do have drain holes for water.