OK we've seen other bikes with Husaberg engines in them. What's out there for Husaberg frames with other engines stuffed in? Should be some crazy stuff. 700cc 2T sidecar engine with wierd exhaust plumbing perhaps?
There is only one 50cc engine that I'd look at ...... the 1967 Suzuki 50cc triple known as the RP68 ... never actually raced, then the rules were changed so it wouldn't be allowed.