Motorcycle Repair: carb, gas leaks, cylinder engine

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
Hi Bill.
 You have a leak in the seals of the float, or the float isn't working properly.  Perhaps sticking or not floating properly.

Pull the carb and check the seals and the float mechanism.  See if the floats really still float.

Let me know how it goes.
Good luck.
FALCON