The hand held utility engine market (as used in chain saws, grass trimmers, leaf blowers etc) is currently dominated by conventional 2-stroke engines covering a capacity range from approximately 25 cc to 125 cc, due to their inherent low cost, light weight, excellent power delivery characteristics and ability to operate at any orientational position.
Impending exhaust emissions legislation for USA and Europe is forcing manufacturers to investigate new technologies to meet significantly reduced Hydrocarbon emission levels while maintaining the functional and customer requirements of these products.
A dominant technology emerging from these investigations is known as air-head stratified scavenging, a solution which maintains the inherent advantages of the 2-stroke engine, achieves the functional requirements of the products and has a very low add on cost compared to existing 2-stroke engines.
This technology is mainly useful for 2 wheeler applications where low cost, high fuel efficiency, simplicity of design and low emissions are fundamental product requirements
This paper presents the principles of the technology, identifies the synergies between the utility engine market and the low cost scooter market, and estimates the potential emissions and fuel economy benefits, that this technology would achieve as a scooter engine compared to an existing, conventional 2-stroke scooter engine.