new needle problem

I know you guys are probably tired of going over this topic, but I need help.

i just put OBEKP needle in and can feel more mid range, but engine stalls when throtttle is blipped open.

the 2000wr has

OBEKP #3position

#42 Pilot jet- stock setting( probably problem)


no airbox cover

stroker dual sport tip on stock exhaust area


Try clip #4 and a #45 pilot jet with the pilot screw at 2 turns.

Think you're gonna like it :)


james... i also am in the process of testing the ekp needle (3rd clip posisition).... ive got a 45 pilot 172 main jet, pilot screw is where ever the dealer put it (havent messed with it yet I live in spokane washington..... iam also running the white brothers e series with 12 plates..... any suggestions? Iam definently getting more pull with this needle, front wheel wants to pull of the ground clear into 4th gear.... but iam also expereancing the same problem stated above if you twist the throttle to fast the bike dies... other than that iam getting very little popping on deceleration... and the bike is actually running the best it has since i got it... any advice would be appreciated....

thanks shane

Ths is great that you guys are giving the EKP a try.

The EKP needle is richer on the straight diameter than a stock YZ426 needle. There are 2 settings that worked for me when trying it out. Your setups are a little different but this will give an idea which way to go. (either richer clip position or increased pilot jet/pilot screw setting)


For needle EKP:

--Clip #3 was best with a #48 pilot and pilot screw near 1 turn, or until the lag goes away (maybe 1 1/2). This a step leaner on the clip than stock YZ426 #4 but it has a richer straight diameter which is an improvement.

--Clip #4 worked well with a #45 pilot and the pilot screw turned out until the lag goes away. About 1 1/2 to 2 1/2 turns out with a stock silencer at the time.

--Clip #5 was way too rich and raspy sounding. This was only run with a #48 pilot and might have worked with a smaller pilot jet. Made the bike kinda violent :) but didn't want to risk fouling a plug :D .

(EKP#3=EMP#4, EKP#4=EMP#5, EKP#5=EMP#6)


James Dean

Thanks James Dean. I will give your suggestions a try and let you know.

James, what MJ did you use for those tests?

I bought an EKP and 165 MJ, which I seem to remember was in the middle of the range?


'99 WR timing, stock carb, 172 MJ, open airbox, GYTR exhaust, So. Cal.


That testing was done with a #172 main jet which was a little rich. Later tests were with #162-#170. The stock YZ426 uses #162 but seemed lean, pulling less hard but revved good.

A #165 is a good middle of the range size. Each bike will be a little different. Right now I'm using a #170 with temp of 55F.


Hey James Dean ("O god of jetting").

You might already know this trick but I thought I would pass it your way.

On a dynojet kit (for my street bike) I got many years ago they gave me small washers that if put one under the clip on the needle jet, adjusted it in 1/2 step increments.

I had found this helpful when fine tuning.

I have read posts and not heard of anybody using 1/2 step increments.


Most guys are lucky to get it in the ballpark first.

I still have washers from doing this 12 years ago on my CR500.

Keihin needles have this 1/2 clip increment in their optional needle codes. EL- is 1/2 clip between EK- and EM- needles. Now if they were available from Sudco we could do this but they are not. So washers are just about as good.

Keihin PJ/PWK needles are available in the 1/2 clip range, so maybe in the future they will be for the FCR... :)


You da man!


James Dean- thank you

my bike rips....

i went to the 45 pilot- 4 th clip- 3 turns on air screw.

the engine dying problem is almost have to blip the throttle very very fast in a tall gear to get it to lag but after the lag the engine rips. I bet if i let the air screw out 3 1/2 turns it would completely go away. is there a limit on how many turns you can make on the air pilot screw?

another observation is i have a 170 mj and it almost feels too rich on top end. (thats easy to fix).

James Dean thanks again the new needle works.


Good to hear you got it dialed in. Welcome to YZ426 jetting and more.

The problem with going past 3 turns is the risk the pilot (fuel) screw getting too loose and backing out. It would be better to go to a bigger pilot jet and turn the pilot screw in about a turn and recheck.

I'm also running the YZ rear fender which vents to the airbox for added flow and a YZ silencer with cool temperatures ~45-55F now.



Is all of this information directely relevent to a 2000 YZ426?

I just got mine and I haven't checked what needle is in it. The runs fine with just a little hesitation. I haven't done too much testing yet. my current jetting is as follows

air screw 1 3/4 out

45 pilot

stock clip 4th position from top

162 main.

I have read alot hear on the wr forum and I am not sure how much relates to my stock YZ. :)



'96 KTM 300e (for sale)

'00 YZ426


Yes, much of it is relevant. There will not be a huge change though.

You have a bigger pilot jet than stock. This richens the mixture at idle and slightly above. A smaller needle straight diameter will also help richen the fuel/air mixture JUST ABOVE idle. The stock EKR is more lean than it needs to be along the straight diameter. Richer needle options are EKQ, EKP, and EKN. EKP and EKN are good choices but EKN may need a leaner clip position. Clark and I have been experimenting. :)

This will help reduce the slight hesitation and give better response overall. It is a small change in the right direction.

James Dean


Thanks, I'll try the different needle and report back. :)



'96 KTM 300e (for sale)

'00 YZ426

hey guys,

is this info the same for a 01 yz? this is my first yamaha so of coarse all my honda and ktm jets are not the right sizes! mine has no hessitation at all, it does stall really easy though here at 1000 ft elev. idle too long and the pipe turns red, i turned the screw out to 2 and it helped starting and idling alot, still seams really lean? any had the bike a week so its all stock i got a 48 pilot from my dealer today, he didnt have a 45 any thoughts?

Recheck your KTM jets. My 45 pilot jet is one I had in my asparin jar for the 96 300 exc. I am reasonably sure the mains are the same too, although I haven't tried yet.


First, what is the stock jetting?? Yes, the pilot and main jets interchange.

I've experimented with just about every combination so look in the manual and post the following:

pilot jet, pilot air jet, needle code (EKR?), clip position, main jet, main air jet.

Most likely the 48 pilot and pilot screw at 1 turn will give more torque and less stalling. Idle it up slightly and it becomes a tractor.


[This message has been edited by James Dean (edited 10-30-2000).]

the stock jetting on the 01 yz is:

168 main

42 pilot

1.25 turns out on pilot screw

needle obejp 4th clip position

NO SH**!!!,

Months ago I posted to use the EKP and a BIGGER MAIN JET.....

-and now the new Yammie '01YZ426 is using the SAME needle and a BIGGER MAIN JET. :D The EJP is only 1/2 clip position richer, a virtual twin that now allows ultra fine tuning. Out of the 90 optional needles in the charts they happened to pick the same. :)

Matt, a bigger pilot jet is called for but be careful not to back it out too far and cause fouling. (see recent posts) With #45 use caution past 2 turns, #48 use caution past 1 turn. The leanest pilot setting that gives good response is better than fouling out.

James Dean

[This message has been edited by James Dean (edited 10-31-2000).]

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