GS 750 PETCOCK

[Anonymous]

IM trying to find adecent diagram of the 1977 GS750 petcock, mines leaking fuel through on the pri and res settings, its only dribbling but it shoudnt be leaking at all!!! (even with a new kit in it)

there is a white thing and a spring in the back (vacume sectioN) and Im not sure of the exact way they locate, the suzuki manual doesnt show anything, abnd neither does the haynes one!

any help please>??

8O

[Anonymous]

The petcock is designed to let fuel flow freely though the Prime and Reserve settings and to stop the fuel flow in the On setting when the engine is NOT running. When the engine IS running, the vacuum pulls on the diaphragm in the petcock allowing fuel to flow while the lever is in the On position. In other words, the fuel will flow in all three positions when the bike is running, and will flow ONLY in Prime and Reserve when the bike isn't running. There is no normally OFF position unless you modify your petcock.

Harrison

[Dink]

Prime is the only position that fuel runs in regardless, On and RES are vacuum controlled.
Dink

[Anonymous]

Umm, am I writing in some other foreign lingo>??>?>

I DID make a typo mistake in the original Q. I meant that the tap was dribbling through in the FUEL and RES positions asked about the insides of the tap and neither of the replies have really addressed what ive asked...

I Know the tap is vac controlled, I know that fuel wont flow etc except in the PRI (prime) position, thats NOT the problem here...

SO...........

I await your reply if you can answer the actual question ive asked!

[Anonymous]

Sorry, I misunderstood. The vacuum pulls the the diaphragm back agianst the spring. The spring needs to be seated properly and the diaphragm should have NO holes in it. If the spring isn't positioned properly, the valve seat in the center of the diaphragm won't seal the gas flow, and it will also leak if there is a hole in the diaphragm. Hold the diphragm up to a strong light to examine it.
I disassembled my petcock when I got the bike and it was several months before I reassembled it. I had forgotten how it went together, but I believe I figured it out correctly. Dink may be correct, though, about it needing the vacuum to flow in Reserve position. I think mine flows in Reserve without the vaccum, but I may be wrong. Then again, it may just be that mine is a 79 and different from others in that regard. I willl try to copy the info from my Clymers and PM it to you.

Harrison

[Hotblack]

Both my bikes have a vaccum controlled reserve.