rmx 250 questions

Well, the last year we received the rmx here in the US was '98, but overseas, it was made at least till '04, to the best of my knowledge. But after '98, the bike changed a fair amount, with new subframe, frame, tank, plastics, and more. Your Japanese import is I believe the version with metal fuel tank and street trim; I'm not sure if its otherwise the same as the post '98 models imported to australia and elsewhere.. I can't offer much help on what parts can be interchanged on those later models, and I'm not aware of anyone on this board that has a japan import either.. But you can always start comparing parts numbers between models, to see what you come up with for interchangeable parts.