I am willing to bet it will come down to some spacers to set the motor off center and....cutting the front fender so it doesn't hit the motor. I have seen some guys put the lifan motors in no prob.( shims, spacers and shoehorn. You might want to join the yahoo s90 forum. Lots of smarty guys. His much do you want for the old engine? I have a "big bore" kit I have been dieing to mess with. I have an S90 build on here. "operation vacation s90" good luck.