Two-stroke engines, which are widely used in small motorcycles, contribute considerably to the overall air pollution, especially regarding hydrocarbons (HC) and carbon monoxide (CO). Therefore countries like Switzerland, Austria and Taiwan R.O.C. have issued regulations for the control of emissions from small two-stroke engines.
First, this paper surveys the emission control standards and the driving cycles for emission determination.
Catalytic systems, composed of small metallic substrates and a precious metal containing three-way catalyst coating, were selected for dynamometer evaluation. Parameters influencing catalyst applications and high catalyst durability are discussed.
Furthermore, an example of a catalytic reactor system already used in series production for small motorcycles to be sold in some European countries and the latest development stage for a 125 cm3 motorcycle are presented.