Let me start by saying I have already perused the forum for an asnswer to this and did not find one.
I was just getting started on the job of getting my F2 on the road. Took the tank off (petcock in the off position) and set it on some cardboard. 5 minutes later I smell gas, check on the tank to find a growing fuel stain. I put the tank on top of an old cooler (I've been planning on throwing away) to catch the gas and checked the valve. It flows really fast on the 'on' and 'prime' positions and flows slower on the 'off' position. I've had bikes that had vacuum petcocks before and none of them did this crap. I'm assuming the petcock seals are shot. Is this a rebuildable thing? Or will I have to opt for a new unit? Oh yeah, the bike did not leak with the tank mounted and hoses hooked up.
Any advice would be appreciated.

 

i had some trouble starting my bike recently and one of the things i looked at was the petcock.I have a 1991 600 f2 and, on mine, if you take the front plateoff( of the petcock)you can get a pretty good look at whats going on inside.....good luck

 

To my knowledge our petcocks should not let gas by in any position inless the vacum line is hooked up. At least mine wouldnt let any by. Just my 2 cents. So your petcock is probably bad.

 

yeah there should not be any gas coming out of the petcock regardless of the position. the vaccum line is the key component that makes everything work. you may be able to fix it, remove the petcock from the tank and dig into those screws. its a pretty simple design so dont feel like you will be overwhelmed. it could be a matter of replacing the seal or possibly just taking it apart and putting it back together, no way to tell till you get in there. good luck!

 

I had the same problem with my F3, ended up just replacing the petcock and that solved the problem.

 

My advice if you choose to take your petcock apart is to use a hand impact driver to remove the screws if they are in there super tight. If I hadnt I would have destroyed mine stripping screw heads with a conventional screwdriver.

 

Sounds like your spring is missing or broken..
If the membrane was broken, fuel would leak out of the orifice of the vent chamber.

The spring presses the membrane to shutoff the fuel. The vacume when the engine is running pulls on the membrane, and compresses the spring,and opens the fuel.