I recently had a major blowout on my 2002 wr 426. threw the rod thru the crank case. top end above the piston still looks good but the cylinder is broke and the crank is chewed up and a hole ion the crank case. looks ugly. I am looking for a new bottom end or maybe a new engine if I can find one. I have found a couyple yz motors but have not located a wr motor. What are the differences other than gearing? I like the wr gearing. can I swap out the gears if I use a yz?