85 GS700 - Fuel Cock/CA Emissions/Racing Idle/Smell of Fuel, etc.

[Jenkin]

New to me is my 85 GS700e with about 25k miles.

Generally has been running fine, although after warming up the idle increases from 1000 RPM to about 2100 RPM. I assume that is due to the intake boot o-rings documented here a lot, or a vacuum leak.

Recently, the bike out of nowhere started idling close to 3500 RPM, and I noticed a very strong smell of fuel (it usually smells a bit gassy in the mornings but who doesn’t?). Adjusting the idle screw did not make a difference at all, so I assumed I had a stuck throttle in some way or the throttle spring was stuck.

First time digging in I discovered some weird things:

1). This was a CA bike, but all the CA emissions stuff is removed.
2). The vacuum pipe that should have been attached to the back of the fuel cock was actually attached to the separator nipple at the top of the gas tank, which made me wonder how the cock was working at all and how fuel was getting delivered through it.
3). I believe there should be a breather tube from the carbs to the air cleaner, but I certainly can’t find anything like that. The air box does appear to have some gas in it.

Got the vacuum tube hooked up again to the back of the cock; started the bike OK. Still seems to be racing at 3000ish RPM, and while running I can really smell fuel, although I don’t see any liquid fuel anywhere and don’t have a drip. I’m pretty confident I’m firing on all four cylinders and recently had the bike in my shop for a new chain and my mechanic didn’t mention a concern about a dead cylinder.

Should I be concerned about that separator nipple on the top of the gas tank which is now simply open?

Should I be concerned that the bike was running fine without proper vacuum to the cock?

All thoughts welcomed - thank you.

[dorkburger]

Not sure about the Ca emissions setup, but it would serve you well to find a manual on that bike and make sure it was removed correctly- as in make sure there are no unintentional vacuum leaks. I looked in my 1150 manual and the Ca emissions stuff looks pretty convoluted. It does state that the the engine draws vacuum thru a charcoal canister that you no longer have - assuming the 700 was similarly set up.

And it could also be typical stuff caused from being old.... I'd eliminate questiins on the removed emissions stuff then go from there.

[chris]

Hi Jenkin, Yes you should be concerned about the petcock delivering fuel when the vacuum line is not installed. Fuel should only flow when vacuum is applied to the petcock unless it is set to prime. Make sure you have proper free play in your throttle cable to eliminate one possible cause of erratic idle. Your bike should not smell like fuel. Like Glen suggested, a service manual is pretty much a necessity.

[tom203]

“...while running I can really smell fuel,”
well ,if you don’t see it, suspect that you’re running rich, so have a look at spark plugs.
fuel in air box might mean your petcock is tired....and is overfilling the fuel bowls at times causing fuel to flow back towards the air box

[Jenkin]

Thanks all for the responses. I agree a factory service manual is invaluable, and I have one. Thanks for confirming that the petcock is probably contributing to the issues I’m seeing so I’ll swap that out.