Abstract: The measures taken to improve the economy and emissions of the two-stroke motorcycle simultaneously are illustrated, which are listed as follows：installing an intake resonator between the carburetor and the crankcase, making use of the exhaust fluctuation effect, adjusting the size of the exhaust pipes to achieve the proper match with the timing of engine, and opening an exhaust regurgitant hole at the piston skirt to introduce the escaping mixture gas into the cylinder for further combustion. In addition, the emissions are greatly reduced by using negative pressure at the exhaust orifice, supplying the gas for the second time automatically by the one-way valve, and mounting a catalytic converter.

Key words: Fuel saving, Motorcycle, Pollution reduction