GS500F Gas drains when bike is off

[drjake81]

I recently bought a GS500F with 30 miles on it that had sat for a year and a half.  The first week I had it, I pulled it completely apart to clean all of the gunk out of fuel system and carbs.  I put it back together and it runs great but I can't stop it from draining the gas tank every time I shut if off (fixed one thing, broke antoher).

Steps to produce problem:
  *Run bike normally with petcock in ON position
  *Shut bike off, leave petcock in ON position
  *Fuel continues to run to carbs (though it should because bike is off)
  *Float in left carb fails to stop gas flow upon filling
  *Left carb floods into airbox and all gas eventually drains to driveway

I've tried:
  *Cleaning out carbs again and again (they're clean man)
  *Adjusted the left float so that it puts more pressure on needle when it floats
  *Ran gas into left carb with bowl off and manually moved float (appears to be fine)
  *Switched the Main and Reserve fuel lines (I'm digging now)

I'm left with:
  *A great bike when it's running!!
  *Removing the gas tank to shut off the gas valve every time I park
  *Thinking about replacing the petcock with a standard shutoff valve so I can be lazy and ignore the problem

HELP!!!11!!

[Admiral Crunch]

Definitely seems like a problem with the float system.  Could the float or valve be jamming before it can close?

[Mandres]

If I were you I'd replace both float valve assemblies.  The www.partsnmore.com kit comes with them and new o-rings for like $12 ea.  Your petcock is also malfunctioning, unless of course you have the hoses hooked up wrong.  I'm actually working on a write-up this weekend to address the terrible petcock on my bike so I'll fill you in when it's ready.

-M

[drjake81]

Awesome, thanks for the advise guys...

[CirclesCenter]

Yeah the stock petcock on your bike might be toast too.

Replace it, thing is trouble waiting to happen.