mikesova, ian harding
The attached picture doesn't show a Schwinn OCC frame, but maybe it'll help. As noted in the posts, the paper thin motor mount straps that are supplied are inadaquate. I'm also with you on not being willing to drill a frame! The pictured bike was my first attempt to put a motorized together. After installing the engine useing the supplied thin metal pieces I tested the engine's rigidity by pushing and pulling on the head. In my opinion, no amount of strap tightening, to the point of breaking the studs out of the engine case, was going to be stabilize the engine in the frame. The engine must not flex or there's no way to avoid problems with chain tension and chain throwing. The pic shows that a piece of aluminum was drilled to the diameter of the frame, in this case 1", and then split to make the two necessary pieces. I realize that it's not going to be easy to make proper, secure engine mounts for your frame. The lot more hand work will be necessary. As for rubber to prevent the frame damage? Might work...but, from what I see it might be worthwhile to consider a sure cure that is both ridgid and non-damaging to the frame.