Many of the owner of motorcycles made modification to their motorcycles to achieve goodperformance, such as increasing compression, changing camshaft racing, change carburator, increasecylinder capacity and etc. in this stuffy the modification vehicle which will be tested is using LPG in fuelsystem with purpose to increase engine performance and to decrease exhaust gas which contain airpollution. In the test of engine performance using chassis dynamometer Dyno dynamics to know theoutput result, such as horse power, air fuel ratio, torque, rpm, and etc. and gas analyzer also to knowingresult of standard from exhaust gas. The result of this modification shows that the power characteristicsincreases and the emission decreases.