1980 leverless petcock-Help?

[keeperd13]

Hello, my 1980 gs850gl has what some threads have referred to as a "leverless petcock." Honestly, I've never encountered this. I've tried screwing the recessed screw both ways to get fuel to flow- No dice. I took it out and cleaned it up a bit. There doesn't appear to be a blockage, but I have not torn it apart, so take that with a grain of salt. For that matter, even if I do open it, is there even a fuel dump setting, to allow fuel to flow without the motor running? If not, how do I prime the carbs? Any help or information would be greatly appreciated.

[Frank Z.]

Your infamous cleverless petcock will need vacuum supplied to the vacuum line to function, either on RUN or PRI. I, uh... suck on mine.

[keeperd13]

So... suck on the vacuum line? Well... whatever works! Haha. So, the recessed flat head. Which way should it be turned and how far?

[Frank Z.]

'Tis a bit odd, but for "RUN" mode, the screw head slot will be horizontal (aligned with the little raised dots), and PRI will be vertical (that's what the top arrow indicates). Doesn't really matter how far, as i don't think the screw is a threaded part.

[keeperd13]

Frank, I owe ya'a beer! I might get to hear my girl run tonight! If the petcock is still good, I just need a battery and (according to the last owner) a CDI.

[Frank Z.]

Happy to help. Next time i'm in PA i'll certainly take you up on the barley pop.
Lotta smart folks here can help you sort CDI issues; all i know is mine works... for now.
Good luck getting her back on the road.

[Nessism]

Frank, I owe ya'a beer! I might get to hear my girl run tonight! If the petcock is still good, I just need a battery and (according to the last owner) a CDI.

Time for some research. The factory service manual details how the petcock works. Basscliff has a free download if you don't already have the FSM.

The leverless petcock has a check valve built into the back cover. In order to get Prime to flow, you need to adjust the slot as mentioned by Frank, plus a pulse of vacuum to open the diaphragm. The check valve will hold the valve open after that (assuming the check valve is still operational - NOT a given), so you don't need constant vacuum.

By the way, your bike doesn't have a CDI. Not sure where people come up with that one, but you are not the first to make that mistake. Starting in 1980, all GS bikes received an electronic/transistorized ignition. Quite different from a CDI. Dirt bikes typically have a CDI. GS bikes use signal generators and an ignitor.

[keeperd13]

Nessim, I guess I'm confused about the CDI. I found it on the bike, and parts sites have the same box, and they call it a CDI too.... so what is it? And I checked BassCliff and I must have checked the wrong download (or it's possible my senile but overlooked it) because It showed a petcock with a lever. Any extra input would be appreciated. And yeah Frank. If you're heard of Roar on the Shore, you might want to swing up for it!

[Nessism]

Nessim, I guess I'm confused about the CDI. I found it on the bike, and parts sites have the same box, and they call it a CDI too.... so what is it? And I checked BassCliff and I must have checked the wrong download (or it's possible my senile but overlooked it) because It showed a petcock with a lever. Any extra input would be appreciated. And yeah Frank. If you're heard of Roar on the Shore, you might want to swing up for it!

Please go back and read what I wrote, then open your FSM and do some reading. All will become clear...

Hint: look in the supplement sections of the manual. Sections 14 & 15.

[OldVet66]

When you turn the petcock back to horizontal, pull the fuel line. You may have to tweak it a little to stop all fuel flow. There is no positive stop on the nylon screw. You wouldn't want to end up with a crank case full of gas.

[keeperd13]

Thanks OldVette!

[hampshirehog]

Here's your tap:

[keeperd13]

You rock Hampshire!

[keeperd13]

Well, I just ripped apart the carbs, cleaned all the jets and passageways, then ripped apart the petcock and reset that.... i'm proud to report she's running on all cylinders!!!