Yz450 head damage

9 replies to this topic
  • tank72

Posted July 30, 2013 - 04:08 PM


Can anyone tell me what would cause this damage?
Engine was rebuilt to new spec 6 hrs ago. Bike ran awesome.
Oil was changed after each hour of riding. I'm just trying to learn how
to prevent this scoring of head.
Thanks in advance for advice!

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  • Yanaco2

Posted July 30, 2013 - 04:31 PM


This happens when the area receives little or no oil flow .This Usually happens after a rebuild where the oil takes a while to circulate and no or very little assembly oil was used!!

  • tank72

Posted July 30, 2013 - 04:33 PM


Thank you

  • DC_Excitement

Posted July 30, 2013 - 05:01 PM


what was the reason for the rebuild in the first place?

if deffanitly wasent getting oil up there. possible a pump failure or some thing is blocking the oil passage going up to the head

  • tank72

Posted July 30, 2013 - 05:12 PM


Thanks Dave .

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  • tank72

Posted July 30, 2013 - 05:25 PM


It was a complete build as the con rod broke and smashed everything.
New cases, crank , rod and piston, rebuilt head,
New cylinder .

  • Slow and Jerky

Posted July 31, 2013 - 02:26 PM


Did you use OEM gaskets?

  • tank72

Posted July 31, 2013 - 05:06 PM


No , aftermarket gaskets.
Thanks for all the replies.

  • Slow and Jerky

Posted July 31, 2013 - 05:10 PM


I had almost the exact problem, i think it was the base gasket. I used a cheap aftermarket gasket and OEM is metal.

  • tank72

Posted July 31, 2013 - 05:52 PM


Thanks very much

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