The new ryobi 26.2 cc, OHV, 4-stroke engine for hand held power equipment applications

This paper outlines the design and construction of a small 26.2 cc overhead valve, 4-cycle engine recently developed by the Ryobi Group of Companies for hand held power equipment applications. Four cycle engines produce fewer hydrocarbon emissions and typically generate better low end torque than the commonly used two cycle. In order to displace the high power density two-stroke technology however, a four cycle design must be cost and performance competitive. Additionally, the engine must be durable and functional at operating speeds in excess of 8,500 r.p.m. The Design for Manufacturability and Design for Assembly methodology used to create the individual powertrain components and subsystems for the new, lightweight power plant to meet the desired cost, performance, and packaging objectives is reviewed.