wr/yz timing?

5 replies to this topic
  • treefrog

Posted April 23, 2014 - 05:11 AM


I have read many posts about how people yz time there bike. I have also read some conflicting threads on the whole exhaust cam 1 tooth clockwise. From what I. undertand, yz timing is 12 pins with exhaust at approx 1 o'clock and intake flush and wr timing is 13 pins with both exhaust and intake flush with head. Can anyone tell me for certain if this is correct? I would love to see pics of yz timing and stock wr timing. I think my 99wr is yz timed but the more I read the more unsure I am.

  • grayracer513

Posted April 23, 2014 - 01:44 PM


The problem is that you are using the pin count between cams as a hard and fast measurement, which it is not.  It will vary between the 400 and 426 models somewhat. Using two WR400 or WR426 cams (NOT an aftermarket auto decomp cam), set the timing to align the E mark on the exhaust and the I mark on the intake with the cam box gasket deck as per the manual.  From that point, the exhaust cam should be rotated in the reverse of rotation direction ("backward" or "clockwise" if viewed from the sprocket side) one tooth.  This retards the exhaust cam, which increase the overlap.



  • treefrog

Posted April 23, 2014 - 02:06 PM


Just making sure. My bike is yz timed. Do you usually need to re jet when you change to yz timing? My top end is strong and the bike hauls ass but it feels kind of "rough" between 1/4 and half throttle.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted April 24, 2014 - 08:41 AM


Yes, you might well have to tinker with the pilot and/or needle a bit.

  • KennyMc

Posted April 24, 2014 - 06:15 PM


I went from a 168 to a 172 main when I put in the YZ timed Hotcams in my ' 07 WR. Also bumped up the piston by .5 and a "clean up" port job.

Edited by KennyMc, April 24, 2014 - 06:17 PM.

  • treefrog

Posted May 06, 2014 - 10:10 AM


Update. Got tired of messing with the timing so I just went back to we timing. Cleaned the heck outta my carb and went to a 172 mj, red needle on 4th notch. Starts first kick EVERY time. Power is smooth with no back fire just a slight bog at initial full throttle. Miss the power of the yz timing but love not having to fiddle with my carb anymore.


Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.