An improved carburetor useful for reducing emissions of small gasoline powered engines commonly used to power lawnmowers and the like has a bypass air inlet and valve for venting amounts of fresh air into the fuel/air mixture to lean the mixture prior to combustion. The enleanment of the fuel/air mixture...http://www.google.com/patents/US5299548?utm_source=gb-gplus-sharePatent US5299548 - Carburetor with lagging bypass air valve
