There is no motorcycle that runs a Yamaha "1250" !!! The "1250" at 600 is really a Yamaha 1200 with a "drop in kit" (oversized jugs with larger pistons). 600 Racing (USLC) is the US distibutor for the Yamaha 1200. The cases are the same, (except for the position of the serial ") carbs the same, everythings the same, except for the oversized pistons. Yamaha does not make a 1250 engine. All this info is according to discussion with Yamaha reps.