none of those motors will be a straight bolt in. just changing the motor alone, won't solve your problem, you would have to change out everything for anything other than a 350 motor ?, as every wire harness, ecu,c.d.i. meter display, all of it..wont just all go together like you want ?. your best bet ?, just find a trx400,trx450, or trx420..and go from there.