Improving the Fuel Consumption of Small Motorcycle Engine with YMJET-FI 2009-32-0049

A construction of the technology concerning fuel consumption improvement is an important problem not only for the four-wheeled vehicle but also for the motorcycle in recent years when petroleum resources are depleted rapidly.

Yamaha originally developed a new fuel injection system (YMJET-FI) and applied the system to a single cylinder, water-cooled and small-displacement engine. In this paper, we would introduce the results of improving the fuel economy with keeping high performance. Improvements were noted in three matters, namely, in the lower load range, 1.Strengthening of in-cylinder flow, 2.Atomization of fuel spray, and 3.Reduction of wall film quantity.

As a result of the combustion improvement by this system and the optimization of the engine performance, the developed model (the prototype model) with this system was able to improve the fuel consumption by 22% on the test cycle of ECE R40-01 compared with the production model with a carburetor as reference, while maintaining high performance.