They came with Briggs 3 1/5 and 5HP, Tecumseh 3 1/2 and 4HP...a whole slew of motor options the early years of Ruttman. I am not fully sure..but I think in 1970 they went to strictly Tecumseh engines. And the kit bikes came with whatever motor you bought. Really odd and neat to hear of one popping up out there. For $25 you can't go wrong.