55 Development of a Fuel Injection System for High-Performance Motorcycles 2002-32-1824

In Sports Motorcycles category, fuel injection systems have been employed more popularly in recent years, and we have been also developing motorcycles introducing fuel injection systems in the category of 600cc - 1400cc displacement. Sports Motorcycles need to be controlled in a wide range from idling to over 10000rpm. Better throttle response, high power and low fuel consumption are also required. Therefore, adding to optimizations of inlet system layout, fuel injection amount, injection timing and ignition timing, the authors have applied to some models electric control devices such as SDTV (Dual Throttle Valve System) that controls intake air amount with secondary throttle valve located upstream of primary throttle valve and SET (Exhaust Tuning System) that controls exhaust pressure by opening angle of an exhaust valve installed in an exhaust pipe to improve the torque characteristics. Furthermore, in order to reduce exhaust emissions, models with three-way catalysts and an O2 feedback system with a lambda O2 sensor have been increased. For utility, we have also developed an auto fast idle system that controls intake air flow rate electrically to increase engine idling speed at starting in cold condition. This paper describes the structures and the merits of these state-of-the-art fuel injection system and various devices.