You could maybe use the shock (valving would be off), the forks could be used with a late model 500 steering stem and the fabrication of a shim in the top clamp. I have been told the ignition could be used, although I have not personally seen this. If you want a more updated k5 you could do as suggested in the previous posts, put the K5 motor in the 250 chassis. It is a sweet bike, much narrower and better suspended. I have 3 500's 2 in 99-02 250 chassis and 1 in an 04 250f chassis. the pictures are upon completion, I have since added new plastic and graphics.