I have read everyones responses, and I do agree with the fact that his tank is too high, however if he fills the tank and it floods the engine he must be using some type of fueling device and not removing the supply line to fill with. It is my suggestion that if possible to pinch off the supply line to the carb, or check your fueling device to see that it is working properly, (i.e. shut off the line to the carb during fueling)

Just my $.02 worth but hey it didn't cost him anything

Don//