Fuel leaking on ground when engine is turned off

[DaveS]

I have a 1986 FZ600 (California model if it matters). A few years ago the valve seals were blown and it was burning oil for a while, and then would not even run. Over the past year I’ve rebuilt the engine entirely but did not touch the carbs. At that time it started but did not idle well, and also leaked fuel on the ground until the tank was empty independent of what mode the petcock setting (on/off/reserve). I then rebuilt the carburetors so everything is cleaned and the floats were adjusted while disassembled. I did not sync the carbs with a vacuum guage but the butterfly valves are very close to equal in position at idle. And I also repaired the vacuum seal in the fuel petcock.. Then the bike would idle well, but would still leak about 3oz (100mL) onto the ground after the engine is stopped. It leaks from the tube on the bottom of the air filter box. I guessed that the vacuum seal is bad somewhere and now only the amount of fuel between the tank and carbs is leaking. The rubber carburetor joints that connect the engine to the carbs were cracking and the vacuum hose from the petcock to the carburetor joints was hard, so I replaced the hose and cleaned the joints and thoroughly covered the joints (after removing from the motorcycle) with high temp silicon caulk as a test to see if that was the problem before spending $150 replacing them. There is no change and still leaks fuel onto the ground through the air filter box about 10-20s after the engine is turned off. I could be wrong, but I do not think the floats are the problem because I think it would continue to leak after the initial 20s even though I did not check the float level after the carbs were re-installed in the bike because I could not find a clear 7mm O.D. fuel line.

I’m kind of out of ideas; any suggestions or answers would be much appreciated. Also, after the engine is warm it is not as easy to start and requires 100% throttle to actually turn over

Thanks,

DaveS

[DaveS]

Looks like I found the problem myself. It turns out to be a bad/clogged charcoal canister. Once I disconnected this there is no longer any fuel leaking nor starting problems. I will be changing the oil shortly since the current oil is likely contaminated with gasoline. On to the next project... The bad fork seals:-)