Evaluation of a low emissions concept on a 50cc 2-stroke scooter engine

A preliminary test bed evaluation of a potentially simple and low cost stratified charging concept is presented for small capacity 2-stroke scooter engines. The end development objectives of the concept are to reduce engine out hydrocarbon emissions and to improve fuel economy while providing engine fuelling by a simple carburettor type fuel metering device. Such a concept, when combined with a catalyst, could achieve significant vehicle emissions reductions with potentially improved catalyst durability. The results presented in this paper, from a preliminary test bed evaluation of the stratified charging concept using electronic fuel injection to provide the fuelling, have shown that engine out hydrocarbon emissions can be effectively reduced at medium to high load without a loss in wide open throttle torque.