Fuel Supply

Most people today use a float chamber system to regulate the fuel supply to the carburetor, with the float chamber positioned at the front of the boat, a small reservoir of fuel at a constant pressure is always available close to the carb. The float chamber is best positioned infront of the carb, if also fitted as centrally as possible, it will help to minimise surge or starvation when the boat is cornering.
One problem that can arise when the tuned pipe is connected directly to the main tank is that with a full fuel load, when you throttle back the pressure in the main tank can blow fuel back into the tuned pipe, this is wasteful of fuel and can bog the engine down. A simple method to stop blownback fuel from reaching the tuned pipe is to fit an expansion tank as shown in the diagram. Blownback fuel collects in the bottom of the expansion tank and as the race progresses it is pushed back into the main tank and is not wasted. A useful extra benefit is that if your boat is upside down after an accident, fuel will not be able to drain out of the main tank into the tuned pipe. (The pickup in the upside down expansion tank is now at the highest point)

An additional idea, but not essential, to prevent too much pressure build up is to fit a pressure bleed valve to the main tank, this could be a fine adjustment remote mixture valve.