Development of Variable Cylinder Management System for Large Motorcycles

The world’s first variable cylinder management system, VCM system, for large motorcycles has been developed. The system uses an in-line four-cylinder, 1 137 cm³ engine as the base, and allows changing of the number of working cylinders from 2-cylinder to 3-cylinder to 4-cylinder. To eliminate an abrupt change of power delivery when shifting number of working cylinders, the electronically-controlled throttle valve (Throttle-By-Wire: TBW) is employed. Coupled with the harmonized control of the intake-and-exhaust valve deactivating system, the smooth switching of number of working cylinders suitable for motorcycles has been realized. As a result, while maintaining the same power output characteristics of the conventional engine, EURO 3 exhaust emission regulations are satisfied while attaining approximately 46% better fuel economy in the New European Driving Cycle mode (NEDC mode). This paper describes the construction, power output characteristics and fuel economy of the engine with VCM System, and the technical innovations for realization of the unique features.