Leaking Carbs?

[Rollin668]

I just aquired a 1990 GS500 with a strange issue going on with the carbs.  It appears the bike will not run unless the petcock is set on "PRI".  It will then leak from the carbs, and only run for a shart time as long as I'm able to keep revs up.  I have the bike in the shgop right now getting a look-over, but I'm wondering if anyone may know a possible route to take.  I do know the previous owner had just "rebuilt" the carbs changing the needles and jets.

Thanks.

[Pkaaso]

I'll bet the floats are out of adjustment.  If they are too high, the bike will leak fuel from the overflow and also will run like crap.  If they are too low the bike with starve for fuel.

Did the PO replace the float needles and seats? Usually you don't need these replaced unless they have sat dry for a long time. Or if they have become caked up with dirt.
They may have rebuilt the carbs but messed up the float adjustment.

The fact that it only runs on PRI maybe because the vacumm hose from the second petcock to the left carburator is leaking or disconected.

Another common problem is the Res and the Main fuel lines getting mixed up at the tank petcock from removing and installing the tank.  Won't cause the problem you described but will cause you to run the bike out of gas thinking your not yet on reserve.

Keep us posted.

Paul

[Kerry]

Yeah, what Pkaaso said.

You may want to check your float height adjustment, whether the shop does anything to the bike or not.  See how on my Float Height Check on a Suzuki GS500E page.

EDIT: Changed link from sisna.com to bbburma.net