Fill a glass of water 1/2″ from the top and swing it in one direction or the other. The fuel in the carburetors do the ssme thing. If there is a problem with a float setting, as fleettwin suggest, extra fuel may be spilling into the intake flooding the motor for a bit. Tubs .
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.