01yz426 broken timing chain

2 replies to this topic
  • gregmanderson78

Posted March 15, 2014 - 02:14 PM


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?


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  • jojo1224

Posted March 15, 2014 - 02:51 PM


They are interference engines, if the timing chain broke then expect at least bent valves but it is most likely a lot worse. If you still want to buy the bike try get it for as cheap as possible so you can make some money parting it out.

  • grayracer513

Posted March 15, 2014 - 03:19 PM


They do interfere.  If the chain is broken, and the valves are bent, it will show up immediately in a leak down test.


If that can't be done, checking the valve clearance will show greater than normal clearance if the valves are bent.

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