From:Doug Miller Electronic:radarsprint -A-
Subject:RE: Still confused about engine sizes. Date:Mon Sep 26 23:27:32 2011
Response to:16374
Joel, you got those right (any that might have confusion are when the 175 was phased in. Doug (the 125 and 165-75(s) have different cylinder studs diameter & spacing)

I am hoping I am doing this right: 50S 125cc /55ST 165cc /58ST 165cc /58B 125cc /61BT 165cc /66BTH 175cc. Any input would be welcomed. Serial numbers are my next hurdle.