Clarity for checking valves

3 replies to this topic
  • Paewraul

Posted June 24, 2007 - 05:17 PM


I have an 01 426 that is YZ timed, and I think I'm gonna try checking/adjusting the valves myself.
From what I've read here it seems like I have to put the timing back to WR to check the valves because the references for TDC are different?

Also, if I choose to install an auto-decomp cam, do I lose the ability to run the YZ timing?


  • Mutu

Posted June 24, 2007 - 07:17 PM


TDC is TDC, regardless of where the cams are timed. TDC is taken off the crank shaft. I put my engine at TDC before the valve cover is even off anyway.
So, to answer your question, no, don't have to change cam timing.

Use a YZ450F auto-decomp cam if you want auto-decomp. The WR450F cams are timed different to the YZ450F, meaning the auto-decomp is in a different position in relation to the cam lobe.

Checking valve clearances is easy, just follow your manual.

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  • Paewraul

Posted June 25, 2007 - 06:06 PM


ok, but do the clearance specs I'm lookng for change when YZ timed?

  • dominator426

Posted June 26, 2007 - 02:22 AM


Valve clearance specs are still the same for a YZ timed WR, or for a YZ;
0.10 - 0.15 mm intake
0.20 - 0.25 mm exhaust


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