My GS has suddenly devepoled a problem tonight....  It no longer accelerates properly.  Here are the symptoms:

(It's an '01 GS with 38k kms (23k miles))

-idle is very low - engine stalls after a little while
-from a stop, I have to rev the bike high and let the clutch out very slowly to start moving
-acceleration is very slow... even in 1st gear when I wack the throttle open, the motor takes forever to rev up
-in neutral, when I freely rev the engine, the rpm'd are lagging behind.

The problem goes away after the bike's been sitting for 20-30 minutes and the bike runs beautifully for the next 20 or so minutes until the problem comes back.  Please help if you can... the long weekend just started and I don't want to be bikeless

Barna

is it getting extremely hot?  is your choke stuck?  it sounds like its getting too much gas.    have you done anything to it lately?

I forgot to mention......

The riders behind me all smelled a strong odour of gas and the guy directly behind me had to wipe gas spray from his helmet.


Jeff, besides carb cleaning/syncing 4000km's ago, there's been nothing done.  The choke is fine.



Barna

Stuck float or some crap stopping the float needle from seating? Pull the carbs and check the floats and seats...

Yes, Check for crap in floatbowls, Float needle seats.  clean it all up, check float Level. Fit a aftermarket fuel filter inline. may save you some headaches

Where is the Gas Tank Vent?... Someone from another board had this theory and seems simple enough to check before I move one.

"Make sure your gas tank vent is not plugged. Sounds like fuel starvation to me. My old GS550E would do that sometimes when held at full throttle on the highway, for, cough cough, extended periods of time. There would not be enough intake vacuum to hold the petcock open and the carbs would empty. It would run like crap for awhile, then when the carbs filled again, everything was ok. Sounds like your tank may be venting very poorly. The carbs starve for fuel, since it is being held in the tank by a partial vacuum, so it runs poorly. When left for awaile, the tank reaches equilibrium, and the fuel flows, filling the carbs and everything is ok for awhile.

But what do I know."

Barna

The tank vent is in the fuel cap. If you remove the cap, there is a 1-way check valve ball that you can hear rattle around.

The vent is *not* the hose that comes off the bottom of the tank! That is the drain line for the area around the filler for water and fuel spills.

Simpler way to check if it is the vent is to ride with the gas cap cracked open, and see if you have the problem.

I seriously doubt if that is the issue. You have a stuck float or crap in the floast valve. A vent problem would give starvation issues, not extra fuel in the exhaust....

check plugs to see if fouled