Carb Needle Profiles for YZ426, YZ400, etc.

Having jetting problems?? Here is a sketch of the varied carb needle profiles. The '01 YZ426 is by far the richest yet at 1/4 to 3/4 throttle.

The '01 YZ426 is using an EJP#4 which is .01-.02mm richer than the '00 YZ426 accross the range. Be careful about going richer on the needle clip.

***** You may need a LEANER CLIP POSITION at higher altitudes or in warmer weather.*****

YZ400 owners should consider the EKP or EKN (P/N 5JG-14916-EP or EN) for an increase in mid-throttle power. Takes it to another level. :)

Use a smaller main jet by about 3 steps going from a D-- needle to an E-- needle.

James Dean

(This graph was provided with the help of Geoff at , and his trick speedo/timer, thanks)


[This message has been edited by James Dean (edited 01-13-2001).]

Ask an engineer for the time and he'll tell you how to build a clock! LOL Good info.


Not to mention the instructions on how to set it. :D

can I just send you the bike and have you fix it up, I can't read even with pictures... LOL :)

Great info though!!

Just picked up and installed the EJQ needle yesterday (part# 5JG-14916-J1) it was on back order for awhile, but boy was it worth the wait! I just THOUGHT it was running good! Since I picked it up a month ago (01 426) I have gone up in steps from the 162 main to a 168, fuel screw at 2 1/4 turns out (stock pilot). With the stock needle, by moving the clip around seemed to address the fat middle, but ir never quite felt right (definetly seat of the pants!) Now the plug looks good (it started out sooty outside and ash white electrode) and just slingshots out of the corners! Being in the Army, we are expected to do physical training daily, and I am fortunate that my boss lets me ride on a track I made at our training site. Too Cool!

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