fuel petcock help

[muslinging79]

ok, i have an 81 750 gs, no manual, sooooo, my question is whats the positions of the pectcock when in operation?

[cowboyup3371]

Welcome to the site, go here to download a copy of the manual: http://members.dslextreme.com/users/bikecliff/

If the lever points forward it's on reserve, down is on, and to the rear is prime. Everything but prime is controlled by vacuum so if the engine's not running and it's in the on or reserve position fuel shouldn't flow. If it does, replace the petcock. Don't leave it on prime for too long or you'll wind up with gas in the oil if you aren't careful.

[muslinging79]

oh thank you!!!!!!! been looking for a manual and having no luck thank you thank you thank you

[Guest]

oh thank you!!!!!!! been looking for a manual and having no luck thank you thank you thank you

There are no levers on this particular petcock. What you will see is a slotted valve. Normal running position for the slot is horizontal, vertical is prime. The engine vacuum controls the petcock's on/off flow. These petcocks can be a real PITA.

[Guest]

Hi and I good luck with your 750.

If you decide to go with a replacement, I have been using Pingels on the old bikes.
I have rebuilt the old stock ones on a number of bikes and I have a GPZ900 and a GS1000 that both have Pingels.

Kind pricey, but after you have to rebuild\replace the stock ones, buying a Pingel doesn't seem like that much of an investment. Below is a link so you can check it out.

http://www.aperaceparts.com/pingel.html

[repulsiv]

If the lever points forward it's on reserve, down is on, and to the rear is prime. Everything but prime is controlled by vacuum so if the engine's not running and it's in the on or reserve position fuel shouldn't flow. If it does, replace the petcock. Don't leave it on prime for too long or you'll wind up with gas in the oil if you aren't careful.

Actually it SHOULD work to have it in prime, as long as the carbs are functioning, but it is a bad idea, because when one carb start to leak you get exactly that, fuel in the oil, or if you are even more unlucky, hydrolock.

So, yes, only use the prime position for priming

[cowboyup3371]

There are no levers on this particular petcock. What you will see is a slotted valve. Normal running position for the slot is horizontal, vertical is prime. The engine vacuum controls the petcock's on/off flow. These petcocks can be a real PITA.

According to the parts fiche the 81 has the standard petcock with lever (I looked before I said my post)

[Guest]

According to the parts fiche the 81 has the standard petcock with lever (I looked before I said my post)

Well from what I can tell from his pic he has posted, he has the E model. The levered petcock will not fit because there is not enough space between the bottom of the petcock and the air box. The only bike the levered petcock fits is the 81 GS750LX. Even the 81 GS750L uses the same petcock as the E.