yep , as far as i can remember , it was a yamaha engine mounted in a seeley frame , it certainly was a very successful almaganation , many top riders scored sucess with these , i think John Cooper was one of the 1st ( if not , the 1st ) to score a major win on one of these machines , at the nw200!, Ray McCullough also had a lot of sucess as well on his silver livried machine.remember the ugp, ;leading Read , Sarrinen, Peter Williams etc.