Only limitation is your imagination (and maybe your tools and resourcefulness) You can pretty much make any motor fit any bike if you got the tools, material, and skill now if you are will to fabricate brackets you can put it on most any frame you can find. I am currently building one...jawa frame, garelli 2 speed motor and tank, honda gold-wing handle bars, vespa seat, peugeot front wheel, a fender of unknown origin and that is just the start...in short it comes down to what you can dream up and what you are willing and able to actually do to the thing.