Jetting question..... To those with a WR426 that went to YZ Cam Timing

3 replies to this topic
  • arctic954

Posted February 07, 2010 - 03:50 PM


Basic question.... when you converted from WR Cam timing to YZ Cam timing.... did you notice any changes in your jetting?

Edited by arctic954, February 07, 2010 - 07:08 PM.

  • wondermuscle

Posted February 08, 2010 - 09:14 AM


Basic question.... when you converted from WR Cam timing to YZ Cam timing.... did you notice any changes in your jetting?

no major changes. The bike pulled a bit harder. If you hear it pinging then go up a main or move the clip on the needle.

I think I was running the following
165 main (maybe a 168)
Stock YZ needle
45 pilot

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  • arctic954

Posted February 08, 2010 - 09:24 AM


yep ---- just finished up with a winter overhaul. Also put in a JD jet kit --- while I was in doing a valve adjustment also rotated the exhaust cam to the YZ position w/ 12 pins. Went to start her up yesterday and she just wasn't running right. And you know.....when you mess with timing and other engine stuff....your mind goes there and not the obvious.

Went out today and dropped the JD blue needle to the 5th position down. (its now 30 degree its cold) She immediately ran better --- but then.....another problem kept happening ---- once warmed up and giving her some full throttle runs in front of my house.....she'd simply die on me....and at times after a full throttle run, she wouldn't hold idle and stall.

Turns out --- only had 1/2 gallon or so of fuel in the tank....AND HAD the petcock on normal --- instead of reserve. This is what threw me on this.....all last summer --- the 'ON' petcock tube was floating around the bottom of the tank disconnected from the petcock.....while I was going through the bike....reconnected it ---- but I'm not use to having one. So, when I started the bike....didn't think about it and put the bike to the 'ON' position. And since you start the bike on its kick-stand leaned over....more fuel got to the carb --- until you stand the bike upright and do WOT.

Stupid hurts.

She's running great now....... and she's rev'ing out VERY nicely now w/ the YZ timing.

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  • GCannon

Posted February 08, 2010 - 10:11 AM


I did not need to rejet for YZ timing I did readjust the idle mixture.


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