Requesting YZ Jetting Recommendation

4 replies to this topic
  • mhays01

Posted April 18, 2001 - 02:17 PM


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.


  • James_Dean

Posted April 18, 2001 - 08:08 PM



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! :)


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  • Tree_Crippler

Posted April 19, 2001 - 07:45 PM


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

  • mhays01

Posted April 20, 2001 - 06:09 AM



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,

  • James_Dean

Posted April 20, 2001 - 07:28 AM



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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