I have no clue how easy/hard it would be to put a 250R motor in the 400EX frame. My friend has a 400 and likes the power of the 250R and has put a bunch of $$$ into his 4 stroke and if he does any mods to the motor he could of bought a 250R motor and have spent less $$$ for the total mod. I know the 4-stroke has its pros and cons, but I have heard of this being done does any one know how difficult this would be to accomplish this task?? let me know how or what you think of the idea. Would there be a power increase or not.

 

Any motor conversion is going to take alot of work and time. Oh and also Alot of money. You will need to weld motor mount brackets. you will also have to design a mounting system for the raditor and exhaust mounts. Price it all out befor eyou think about this conversion. What is wrong with the 250r frame????