Your best bet would be to fit YZ'S suspenders to the xt chassis, the front end bolts straight up, the rear end takes a little bit more work, go with a an it 250/465 swing arm as the xt snail cam adjuster rear wheel fits straight in, don't use a 175 arm as they drive on the right side, the it shock should also fit fairly easy although the resoviour might cause some probs, all in all a much easier conversion than trying to fit a four stroke motor to a YZ's chassis.