US Patent 7467785 Auxiliary fuel and air supply in a carburetor

A carburetor includes a fuel and air mixing passage with a throttle valve therein, and a bore with a valve therein defining in part a valve actuation chamber and a separate fuel and air mixing chamber in communication with the fuel and air mixing passage at a location downstream of the throttle valve. A fuel passage and an air passage are in communication with the fuel and air mixing chamber. A purge apparatus is in communication with the valve actuation chamber and is operable to move the valve to an open position to open the fuel and air passages to the fuel and air mixing chamber such that a fuel and air mixture may flow from the fuel and air mixing chamber to the fuel and air mixing passage downstream of the throttle valve.