Gas leaking from exhaust.

Hello all, I recently just bought a 1980 xj650 and have been having problems with it. First got the bike, it was leaking gas out of the air box... So I took off the carbs and cleaned them, cleaned the rust from inside the gas tank, put everything back on, and yay! No leaks from the carbs or air box.. But now, leaking from the crank shaft casing.. Gas was mixed with the engine oil. So I drained it, put new oil, and no more leak from the casing but now gas is pouring out of the exhaust. A few people online said it could be the vacuum line or the diaphragm in the carbs? Not sure what to do or what my best option is.. Any help?

 

Time to rebuild the petcock, and re-evaluate the carbs. One (or more) of he carbs has a leaky fuel inlet needle that is allowing fuel to flow in even after the carb is "full" of fuel.

The petcock (as long as it is not set to the PR (prime) position, SHOULD shut off fuel flow when the engine is off. BUT, even if it is in failure mode and continues to pass fuel when the engine is off, then the fuel inlet needle valves SHOULD seal off fuel flow into the carbs.

 

Thanks so much I'll look into that. I also read up that the float could be getting stuck and just letting gas in and filling up the bowl.