James Dean 5JG-14916-EP-00 Needle


Today I ordered the Yam 5JG-14916-EP-00 needle to try in my YZ timed 99 WR 400. I'm running the FMF PB / PCIV-2 exhaust and the DSP CF air box. Yam lists this needle as a EVP so I asuming it has the same straight section diameter as my current DVP and will have the same mid point break on the tapered section (L1) but will have a steeper taper angle increasing fuel metering between 3/8 to 3/4 thorttle. I'v been running between a 175 to 182 MJ depending on altitude.

I will be testing at 1200-3000ft altitude and am considering starting a clip positon #3 from the top and using a smaller sized main jet probably a 175. I will be using a 50PJ.

Based on your efforts does this sound like a good starting point??



Run the pilot jet that you have been using the most at that altitude. #45 or #48 is what I would run in my 2000WR. Clip #3 is also a good choice to start with for this needle. Main jet will need to be downsized and 165 to 175 is a range to expect.

---Note: The parts listing says EVP but the needle is ACTUALLY EKP! Yes, you have ordered the right part. Yes, the tapers start nearly the same distance from the top of the needle.


My last ride out was 85 miles of single track with trips over three 6000ft ridges starting from 2-3000ft. The elevation gain on TOPO mapping showed 16000ft net elevation gain and drop for the day. The big hills were a good test for the mid to full throttle range. The exact needle you are getting is what was used, clip #3. It worked perfectly, roll-on torque at 3/8 to 3/4 throttle was excellent. Less throttle is needed to get the same pull. No bogging or hesitation. Still can't whack it hard open from idle, but anything slightly above it jumps. Back to back with a '99 WR w/FMF PCIV-2 seemed like the '99 was smoother, but not pulling as hard at mid-throttle. Both bikes were YZ timed.


Jetting was:

#45 pilot - 2 turns/#75 air jet

EMP#4 (same as EKP#3)

#172 main

Stock muffler/no baffle/YZ timed/no airbox lid


Next ride:

#48 pilot - ? turns/#100 air jet

EMP#4 (same)

#172 main (same)

YZ muffler/YZ timed/no airbox lid


This is about as good as it gets, getting any better will take a custom grind on the needle. I have 2 riding partners with a YZ and WR to give their bikes a chance with EKQ and EKN next time out.(2 weeks?) Hope it works for you too.

James Dean


What jetting was the 99WR 400 running you were comparing against??


Fuel Screw=


Clip position=

Main Jet=



Fuel screw=2 1/4



no airbox cover

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