2-stroke cycle gasoline engines are prone to irregular combustion at low speeds and under light loads. In motorcycles, this causes vibration of the body and adversely effects riding quality.
A system for quantifying such irregular combustion was established so that the riding quality of a motorcycle could be assessed through a bench test of its engine.
It was verified through a series of tests performed on this system that there is a significant correlation between the actual riding quality and σPmi assessed by the system.
Accordingly, this system has become an effective means for predicting the riding quality of a motorcycle through a bench test of its engine.
Making use of this system, it was also found that some of the typical engine operating factors, such as the air-fuel ratio and ignition timing, have optimum values for reducing irregular combustion in engines under certain conditions.