Wossner piston PW50 40.5mmYamaha PW50 models from 1981 to 1997. Designed for two stroke engine rebuilds requiring an increased bore size, it provides exceptional durability and precise thermal expansion characteristics. Features Forged construction ensures superior strength and wear resistance Elliptical design delivers a uniform bearing surface under heat expansion Efficient heat transfer from combustion chamber to cylinder walls Prevents piston collapse by evenly