[tom hand]

Or does the motor still have the heat riser valve on the exhast manifold? If it sticks closed it could overheat the carb, (its designed to warm up the intake when it's cold) causing the gas to boil in the carb. One pipe blocked on a dual exhaust would do the same thing. Next time it does it pull the breather and see if the accelarator pump will sqirt gas to help tell if it is a fuel or ignition problem.