I found a craigslist 2001 yz426 that has a broken timing chain. I wanted to know if these engines are interference(do the valves open far enough to interfere with the piston if timing is lost) and does this failure possibly damage the head, cylinder, or case materials. I am fine with rebuilding it, piston, cams whatever, i just dont want to have to get any machining done or try and buy new casting parts. Any ways to determine any of these things before buying the bike? Thanks.