I have a quick question for people. My friend just bought a 2000 yz426. The previous owner didn't do much in the way of up-keep on the bike, and now my buddy is faced with a total engine rebuild. While he has the engine apart and the cranked ripped out, what are somethings we should look for when we put it back together? and what are some of the best mods we could do to the bike when we put it back together?