Hi ppl.
I just bought a 91' Gs, And after a while started noticing a few problems...
After the bike Has warmed up a little (Maybe after 30 minutes or so of driving) it will suddenly loose power acceleration Etc, Iv'e noticed That this is a common problem if The petcock is set to On Or Res, But i was actually on Pri, Another problem i had was when i tried to accelerate (After a while again) it wouldn't accel normally and just slowly drag up and the engine would "Jump" (Rpm Would go up and down) Although i kept the Acceleration Constant.  (I noticed that the first problem sometimes occurs after i get to really High rpms (Around 11,000)  it would all the sudden loose power. Also,  After riding for a while the engine would idle at higher Rpm's Than At the beggining (Around 3000) And the engine would die if i tried to lower it back to 1,200. I cleaned the carbs and changed the air filter. Does anyone have any idea what could be causing this problem?
I did search the forum without Any luck. I would be grateful For any usefull Ideas..

Youe description is a little confusing... But I believe you are lean down low... at idle... After 30 mins of riding... would seem to suggest you are a bit rich, but unless you have very much bigger jets in it I'd say you probably have floats set a bit too high. Now right after the 11K rpm... Might be fuel starvation... Your petcock could need a cleaning... and may be check fuel lines as well.
Cool.
Srinath.

I think the main problem i noticed is the engine power loss
everything works fine for a while (Petcock set to PRIME)
and all of a sudden starts working really sluggish
The engine sounds very low sounding and very weak (It won't die but will run very poorly..) i think it happened once exactly after i red lined it..
didn't notice any exact patterns for the problem...

I suspect your flow... Somehting is prolly blocked or hose kinked and check your tank venting ..
Redlining wont create sporadic problems...
Cool.
Srinath.

Do you have any rust in your gas tank?

It sounds like you're starving for fuel, but if there's plenty in the tank then you need to consider the delivery system.  The sporadic nature of the problem suggests that particles in the fuel are blocking the flow (in the carbs) and then being dislodged.

There are all kinds of things to try, if you're the patient type:
 * Cleaning the carburetors (the jets, especially)
 * Checking the float height on both carbs
 * Installing an inline fuel filter
 * Bypassing the frame-mounted petcock
 * Installing 5/16" fuel lines for more flow
 * Cleaning the filter inside the gas tank
 * More...?

But I'm not surprised that it happened after red-lining that one time.  That seems (to me) the most likely time to experience fuel starvation - even if everything is "clean as a whistle".  That's when you're sucking the greatest volume of fuel through the system, right?