Importing a motorcycle to the U.S.: My experience is that it is/is not possible.
I tried and was thwarted by EPA/DOT -- the motorcycle didn't have the required certificates and was not allowed. BMW says that they provide North American motorcycles that are the same (legally) for U.S.A. and Canada -- but, only have the stickers (and certification) for the country for which they're intended to be sold. Ostensibly, you can get the importer to provide you with the correct documentation for the licensing bureau -- I couldn't.
Alternatively, you can state (written/signed document) that the m/c in question is for racing only -- off highway use only. Then, somehow, later fudge a title of some kind (w/paper from a crashed bike, or...?).
Then again, I personally know a guy who brought in a Canadian motorcycle and licensed it and rides it around. When I asked him about it, he said he had it in the back of a pick-up in the middle of the night at a remote border crossing (and drizzling rain, too, IIRC) and all the paperwork was signed and passed. I still don't know how he got it through the DMV/MVD? But, he did.
Then, when all else fails, there's a company (actually, 2 guys) in Washington D.C. that will walk your vehicle through EPA/DOT certification. One guy is a mechanic who certifies the necessary modifications have been made; while the other guy wines and dines the bureaucrat as necessary to insure all the paperwork is in-order. This all costs considerable money -- your money. Yet, I personally know a guy currently riding a non-U.S. certified Russian bike done this way (he bought it in Finland).
Good luck.
