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I have 1982 yamaha maxim 400. It has been sitting for year and I have recently got it running again. However after riding it and parking it in the garage gas starts to leak out of the back (air intake) of the carburetor. It smells up the garage and even gets in the house and REALLY stinks. In fact I was up at 6:30 this morning and noticed the smell. I had to move the bike outside (in the rain ). Anyone know what causes this?

I think that the petcock is leaking fuel. Also the carb that is leaking has a sticking float or a needle and seat no sealing the fuel off. Good Luck!!!

after reading some other posts I think that my floats might be adjusted too high. I am not positive it is the petcock because it seemed to be in proper working order the last time I drained the tank (although I will not rule it out, that's for certain). The leak is actually coming out the venturi end between the air box and rubber sleeve that clamps onto the carburetor.

the needle seemed to move freely but who knows what's going on in there now.

Thanks for the response.

If your petcock has an "off" postion, that should take care of the problem. If you have a vacuum petcock, it should also not send any fuel to the carbs in the "on" or "normal" position, unless it is getting vacuum from the engine.

I agree that your floats a probably set a little high, which is what causes the fuel to exit the intakes, but if the petcock is working properly, you should be able to shut off the flow to the carbs anytime you want. Sounds like you have two problems (fixing either one will fix the problem).

the float valve seats on the carburetors have o rings on them.
they will let gas leak by the seat and overfill the float bowls even if the float needle is sealing.many people dont know this and clean their carburetors and set the floats at the correct height and still have problems.if you pull. the carbs check the float height on all of them if they are reasonably close to each other it may be the o rings leaking.

I pulled the gas line (to the carburetor) off the petcock and ran another line from the petcock into a container and left the bike for the day. When I got home later that day and, sure enough, the conainer was almost full of gas. this was while the petcock was in the fuel position, so it shouldn't have leaked. I pulled the petcock apart yesterdy and found a broken o-ring. After I get that taken care of I'll double check to see if it still leaks and the floats need to be adjusted.

Thanks for the help all!

Glad to see you getting that 82 Yamaha on the road

What a year

What a year

Glad to see you getting that 82 Yamaha on the road

What a year

What a year

not sure how that posted twice...

I've had it running in spurts a couple of times and it is so much fun to ride. When I roll back on the throtle is takes off and gives me more than enough power. I am excited to get it all dialed in.