motor stop

3 replies to this topic
  • YZ450F4

Posted May 18, 2011 - 10:08 AM


I have a yz450 and it has just been rebuilt 10hours ago. i was out ridin the other day and on decel it stalled. couldnt get it started and it kicked back like a two stroke. i was not giving it throttle. Took it apart and the oil filter is covered with metal shavings. Under further inspection, the cams have groves in them but there is nothing in the head to rub on there? The exhaust cam DID NOt have the clip in it that goes in the cam cap though. But i dont think i over torqued the cam caps because i have a YFZ450 quad also and ive checked the valves on it and had to retorque them too. Help please. What do you all think the problem is and what needs to be replaced besides the cams? Anyone else ever had this trouble?? Thanks

  • grayracer513

Posted May 18, 2011 - 10:57 AM


If the exhaust cam had no clip, there's no saying that it was correctly aligned left to right, and the sprocket, chain, and/or one or both cam lobes may have been hitting the cylinder head somewhere. You may have to send the head out to get the cam bores refinished, and replace anything that suffered any damage.

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  • YZ450F4

Posted May 19, 2011 - 09:54 AM


How much would that be to get it refinished? and i know head are pretty expensive. like 900 bucks i think for a new one.

  • grayracer513

Posted May 19, 2011 - 10:01 AM


A lot of times, damaged cam bores get fixed for around $250-350.

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