Abstract
With the rapidly development of motor technology, the environment pollution caused by motor exhaust gas and noise gets more and more attention. The paper presents the experimental study on influent factors of Motorcycle muffler noise reduction, including changes of length and radials of the muffler pipe, the ratio m of expand cavity, the size or shape of tail pipe, the position of isolation plate inside a cavity, and verify of the total volume of the muffler. Rules of muffler structure design are studied.