PAUL5992, YOU ARE RIGHT,,.. dont wory about the differance I would be willing to bet that the 55 cylinder would fit on the 50 crank case (it could be) that the 50 series cylinder and piston is not being built but the 55 is,. if we could get the info from the mfgr. as to why ??? the 50 is no longer around . or possibley the engine designer found the 55 is a better and stronger engine ?? things to think about and make one say hmmmmmm I wounder !?



JIM