Recently bought a 99 YZ400f with a very damaged engine. The chassis is 100%for complete and in Good shape. I was going to part it but my mind started working and I thought what about lowering the suspension a little and swapping in some sort of old school bulletproof torque monster 4stroke like an XR400, TT500 or even an old twin like a cl360 . I know there will be considerable fabrication and it will be heavier. But im thinking tractor torque with decent suspension. Well flame away!