So are the square 4 strokes that people on here use, but they make motor mounts for them. I myself make all the mounts for any bikes I have made, I have put many motors, Chainsaws, Weedeaters, random big fat B&S motors. Basically pretty much any motor can go on a bike, but you are almost always going to custom fabricate some parts or hope they are available from one of our many vendors.