200 big red engine doesnt fit unless you lose the starter/notch the frame as stated above and the high low selector hits the frame right next to the chain adjustment also an area under the selector touches the frame can easily be made to work thought if you do alittle grinding but its not a bolt in and go like a 185 or 200 with out electric start. I know i just spent 2 hours trying to wrestle a big red motor in my 200x roller