Investigation and Tuning of the Exhaust System of Small Two-Stroke Cycle Engines

Oscilloscopic investigation of the pressure phenomena in an exhaust system of a small 2 stroke cycle internal combustion engine shows that a low pressure at the exhaust port during the middle of the scavenging period and a high pressure toward the end of the charge changing period is advantageous. The low pressure can be created by means of an exhaust diffuser and the high pressure by means of an orifice installed at a suitable distance from the exhaust port. Both phenomena produce a desired increase in engine performance. The development of a diffuser exhaust system is described.