Heres my perspective - if this XCR is a high mileages sled and has never been taken apart .. what happens is over time .. the skirt gets wear and tear and eventually it will start making a rocking motion between the piston and the cylinder. Usually when a skirt breaks off, while running - it will take the crank out. If your pistons is cracked .. do not reuse those pistons. Replace them all and make sure they are all within specs - check crank to make sure everything is ok there. If it was me .. I would replaced the waterpump bearings, replace the crank seals with a refresh the top end - WL.