He has a website, which has a bike list with nothing but Kawasaki Z-1's listed, KZ1000's and H1 and H2's. The Suzuki, Honda and Other lists are empty. Not sure, but perhaps you can call the BBB or Chamber of Commerce for Torrance, CA. and ask about his business. A cashiers check isn't all bad, as long as it is from an account that has money in it, and it belongs to him.
I received a check from 5/3rd bank here that was forged, and counterfeited. Be diligent when dealing with checks, and call the bank it is drawn on to check the account. He may be legitimate, but on CL it is never a bad thing to check up on someone.
Charlie