Requesting YZ Jetting Recommendation

I’m getting ready to go to YZ timing. I’ve tried to read every post concerning this topic and would like some final options and tips on jetting.

Current setup is a 99WR, FMF PC IV2SA, PowerBomb, TwinAir, Air Box top removed, Altitude 0-1000FT , 50% MX-50% Trails.

It seems like a popular configuration would be DVP#4, PJ 48, MJ 172, Fuel Screw 1.5. But, based on the post the E** series needles might be interesting.

I’m also planning de-octopussing with the PAJ #100 and YZ Start jet #65.

I’ve ordered the following parts.

5BE-14916-DP-00 NEEDLE (#DVP)

5JG-14916-EN-00 NEEDLE (#EKN)

5JG-14916-EP-00 NEEDLE (#EKP)

3TJ-14948-06-00 JET (#48)

7A9-14943-27-00 JET (#100)

3TJ-1494F-13-00 JET (#65) (YZ STD) (Start Jet)

4MX-14943-40-00 MAIN (#165)

4MX-14943-41-00 MAIN (#170)

4MX-14943-42-00 MAIN (#175)

4MX-14943-93-00 MAIN (#178)

Any advise or opinions would be appreciated.



Here are 2 options to pick from:

1)Needle DVP - More responsive than stock, clean running, controlled revving, lean in mid-range relative to "standard" Keihin needle.

#48 pilot jet (**)

#100 pilot air jet

3/4-1.5 turns out

DVP needle clip #4 or #5

#172-#180 main jet

other jets stock

2)Needle EKP or EKN - More mid-range power, wheelies quicker, "The engine and the power that it produces now feel more wired to my brain"(John in L.B.- see "EKN needle results"), not always as tractable, '01 YZ426/250 use this, "standard" Keihin needle taper.

#48 pilot jet (**)

3/4-1 1/4 turns out

#100 pilot air jet

EKP#3 or #4 clip (or EKN#3 or #4)

#165-#172 main jet

main air jet #200 (or removed with #172 main)


(**)A #45 pilot jet may be preferred at higher altitudes and warmer temps, expect 1 1/2 - 2 1/4 turns out on pilot screw.

An adjustable pilot air screw is a good addition also.

Good Luck! :)


Great answer James! I just printed it out so I can just give my friends a copy. Thanks.


Thanks for the excellent reply.

It's exactly what I was looking for. It was a great answer that consolidates a lot of testing and experimentation into information that usable by everyone (e.g. novices like me). I think that the usability is proven by Tree Crippler’s intentions to give copies to his friends.

Many Thanks,



Your willingness to purchase all the jets and needles was worth giving a more complete response. You're welcome. Feel free to post questions if you have any difficulties getting it adjusted.


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