The effects of camshaft modification on engine performance in automatic transmission motorcycle

Automatic transmission motorcycles have become a popular transportation choice in many countries. One of the methods to improve engine performance is by modifying the camshaft. In this report, we characterized the engine performance (power and torque) after modifying the camshaft’s Lobe Separation Angle (LSA). The valve opening duration and the overlapping process became the main variables to be adjusted. The experiments used a 4-strokes engine with SOHC (Single Over Head Camshaft) taken from an automatic transmission motorcycle with 110 cc type. The actual engine capacity was 108 cc (with a bore of 50 mm and stroke of 55 mm), and the compression ratio was 9.2:1. This engine has a maximum torque of 13.28 Nm and a power of 9.1 HP (at 5393 RPM). To evaluate engine power and torque for both compared camshafts, a dynamometer was used. From this study, we can conclude that LSA plays a vital role in determining valve timing diagrams, thus influences engine performance. Power and torque curve peaks of the modified camshafts are obtained at a lower speed than that of the standard camshafts.