YZ vs WR jetting?

2 replies to this topic
  • Jerrit

Posted May 01, 2002 - 09:50 PM


I bought a used 99 WR 400 and the guy said the only thing he's done to the engine/carb is put in YZ Jetting...what does this mean? I thought the timming was the only engine/carb difference on 99 WR/YZ 400's.

The bike runs great but has a 1 second delay when in neutral and/or clutch in and I quickly crack open the throttle to 1/2 open or so.

Is reducing the squirt duration the only way to resolve this issue or could a jetting change do it?


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  • James_Dean

Posted May 01, 2002 - 12:27 PM


The jetting has always been different between the YZ and WR. The YZ jetting has changed from year to year also.
Try adjusting the fuel screw in(leaner) or out(richer) to help the bog. Then needle clip position, probably a step richer.
The accel pump change is helpful, but not a requirement.

[ May 01, 2002: Message edited by: James Dean ]

  • Rich_in_Orlando

Posted May 01, 2002 - 04:37 PM


Hey, I know! Why don't you take off your carb and look at the jets? THAT would tell you what your jetting is. Then you can see for yourself what "YZ jetting" is.

Seriously, when I went to YZ timing, I had to lean the jetting before it ran right.


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