Motorcycle Repair: carbuerator, gas leaks, float bowl

Question
I just finished fixing up an old J.C. Higgins 1940's bike with a 1 cylinder engine, and it runs fine, but when I turn it off and shut off the gas to stop the flow from  the tank, gas leaks out of the carb mouth until the carb is empty. Do you have any idea what it could be, and what I could do. Thanks  

Answer
Bill,

Sounds like you may have a couple of problems here.  The first being the tank's petcock.  Be sure the valve is working correctly and you are indeed stopping the flow of fuel.  Second and more importantly, your needle valve and/or floats are not operating correctly.  If your floats have leaks and are just sitting at the bottom of the float bowl or are set incorrectly the fuel level can rise above the barrel.  Also, if the needle valve is stuck or not sealing you may run into the same problem.  It's possible the float bowl is alowed to overfill but the engine is using the supply fast enough for you not to notice and once the engine is killed it catches up and overflows.  You'll most likely need to dissasemble the carb and clean and adjust the floats and needle.  I don't have any specs on that bike, you'll have to do some web research to get the proper set up tolorances.

Hope this helps,
Mike