I just bought a 91 GS500. Been sitting for 2 years. I cleaned the carbs, tank and fuel valve, then re-assembled. Next morning there was a gallon of GASOLINE in the CRANKCASE(Which had happened while it sat for 2 years also).
IS IT NEEDLE AND SEAT, OR IS IT THE FUEL SHUTOFF VALVE? OR...DOES THE VALVE HAVE AN OFF POSITION? WHAT DOES PRI stand for?

(I don't actually have a bike - yet - but I think I've heard this answered enough times.  Someone will correct me if I'm wrong).

PRI stands for PRIme.  It lets gas run straight into the carbs, you use it when the system is dry (been winterized).  Some people also put their bikes into PRI when they run into high speed fuel starvation issues.  The ON and RES positions work on vacuum.  Letting the bike sit with PRI on is a bad idea, since the gas wil lruin all over everything.  

Or something like that.

That is a unusual problem, when the ignition is off no fuel is being pumped into the carbs, I don't see how that's possible. I would take my bike to the dealer if that was happening.

Yea, PRI will let fuel flow all the time, but if it is leaking you have a problem w/ the floats sticking  

Even on PRI it shouldnt leak at all. If it does you need to check the floats  

Also, turning it to the ON or RES position should shut off the flow unless the bike is running  :mrgreen:

Can anyone post an up close picture of their fuel shut off valve, so I can see which way my valve should be turned!! I can't figure out if mine is always on reserve... does that matter?  :dunno:

Yes it does, if you have a full tank of gas and have it on reserve your bike might run out of gas while you still actually have a full tank.

The knob should have an arrow on it.

Up is 'Prime', pointing towards the front of the bike is 'reserve' and pointing down is 'on'.

I had this problem with my GSX400 it was due to a bad o-ring on the vacuum activated valve in the petcock and stuck floats.

Quote from: maxwellfCan anyone post an up close picture of their fuel shut off valve, so I can see which way my valve should be turned!!

See this thread for annotated photos.

Quote from: rclzYes it does, if you have a full tank of gas and have it on reserve your bike might run out of gas while you still actually have a full tank.

Uh, what?

I thought having it on reserve will let you go through that last gallon but otherwise run normally, the only danger being that if you DO run out of gas, you'll (naturally) have no reserve left??

Isn't it just that the reserve line is at a lower point on the tank?

Quote from: red_philThe knob should have an arrow on it.

Up is 'Prime', pointing towards the front of the bike is 'reserve' and pointing down is 'on'.

Noobs reading this: Nota Bene that it might be different by year. On my 2001 pointing up is RES, pointing toward the rear is PRI, and pointing down is ON.

make sure the float bowl drain screws are sitting correctlt, they are slightly shamfered and if not sitting right the floats will drain straight on the engine

Quote from: milo

Noobs reading this: Nota Bene that it might be different by year. On my 2001 pointing up is RES, pointing toward the rear is PRI, and pointing down is ON.

Thats how it is on my 05

check the fuel shutoff valve. NOT the petcock with the lever, but the actual shutoff valve. It's under the tank, so you'll need to remove the seat, rear plastics, and take your tank off. It's a little dealy underneath by the hoses with a flathead screw for on and off. Make sure it's on.

I have heard of this problem on other suzuki's. The easy fix is real fuel shut off valve. keeps that from happening.

Quote from: natedawg120

Quote from: milo

Noobs reading this: Nota Bene that it might be different by year. On my 2001 pointing up is RES, pointing toward the rear is PRI, and pointing down is ON.

Thats how it is on my 05

2001 on are different than earlier bikes.

Quote from: mjm

Quote from: natedawg120

Quote from: milo
Noobs reading this: Nota Bene that it might be different by year. On my 2001 pointing up is RES, pointing toward the rear is PRI, and pointing down is ON.

Thats how it is on my 05

2001 on are different than earlier bikes.

Have links to pictures gone out-of-style all of a sudden? :dunno:  Like I said eight posts back:

Quote from: KerrySee this thread for annotated photos.

if you leave the percock set to prime and have a full tank or almost full,  the pressure from the gas is more than the floats can hold back so gas will constantly seep into the carbs,  its got to go some where so it will run out the over flows on to the engine and also drizzle out of the carbs into the cylinders, then it seeps past the rings and fills the crank case.  in short,  dont leave it on prime