Jetting Compares

[Chukkar]

I cant find a U.S. stock WR vs U.S. stock YZ jet setting chart. I would like to know because when I remove my airbox cover, the bike stalls badly when the throttle is cranked on quick. With stock WR jetting and cover it doesnt stall at all. Are there other changes required to remove the cover besides the jetting? ?

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[Hick]

It depends on the year. If you are talking ’01 then the main difference is the needle, the WR has a much leaner needle (DRR) vs. the YZ (EJP). I think the main may actually be one size richer (165 vs. 162) on the WR but the pilot is the same. The only other difference I’m aware of is the pilot air jet (75 in the WR, 100 in the YZ).

If you remove the lid and uncork the exhaust you should swap the YZ needle in there, the stalling you are experiencing is due to an overly lean condition on the needle.

If you were to also change the cam timing to YZ spec (and cut the gray wire??) you will basically be riding a WR with a YZ motor in there.