Carb Needle Profile Comparison YZ vs. WR

56 replies to this topic
  • James_Dean

Posted January 13, 2001 - 07:15 PM


The YZ426 has a much different carb needle than the WR's. If you decide to uncork your WR and go with YZ timing, it may be worth looking into the carb needle too.

Expect it to feel like you just pulled out a second baffle, a boost in the mid-range.


The EKP#4 or EKN#4 are my favorites in the '00WR400. The '01 YZ426 is using EJP which is 1/2 clip richer.

Suggest using a #48 pilot, 1 turn out, #100 air, and #165-#170 main.

James Dean

(Sorry Yamaha, the secrets out!! There is more power to come from a triple taper needle, but that is still under wraps for now)


[This message has been edited by James Dean (edited September 26, 2001).]

[ January 13, 2002: Message edited by: James Dean ]

  • Clark_Mason

Posted January 13, 2001 - 09:05 PM



As you and I well know there is performance in "TINKERING" and I support your conclusions relative to needle selection and jetting in general on this application. The "E" series needle in combination with the YZ timing can be a real eye opener with its more agressive throttle respponse. Howerver, I still feel that on the 98 and 99 WR's with YZ cam timing the DVP needle is hard to beat as far as a execllent overall predictable throttle response needle is concerned.

Happy trails all as I maybe selling my 400 and moving on with my HONDA XR650R. I will be another development challenge to sort through the hype of all the aftermarket BS and most of it is BS.

Lets see a totally tricked out 99 WZ 420 California plated bike with the proper VIN to continue its street status forever and I'm bored and now building a very interesting XR650R. A very heavy exchange if I do say so.

Right now streeted with a full Baja Designs Kit and My WZ 420 is at 252lbs.
O'well the Honda is just another project bike.


[This message has been edited by Clark Mason (edited 01-13-2001).]

  • MN_Kevin

Posted January 14, 2001 - 02:04 AM


Maybe you should wait until the release(?) of the new Honda 4 stroker...??? I saw in Dirt Rider, Suzuki is now working on a 4 stroke MX bike.[

  • James_Dean

Posted January 14, 2001 - 09:06 AM



The OBDVP carb needle is an excellent performer too. We have shared a great deal on this topic outside the visibility of the forum readers. It has been a pleasure.


  • Shane

Posted January 14, 2001 - 10:42 PM


Yes James... your definently right about that ekp needle... Changed to that last summer on your recomendation and it felt like i had a different bike! the thing pulled like ya read about.... I will be going to the yz timing in the next few weeks (as well as tearing my bike completly down for a good greasing and cable lubing) I think while Ive got it torn down Ill attempt to do the forks myself ( new springs/ maybe a new gold valve) any problems to speak of with this mod? I saw earlier that you where doing some suspension mods... curious on the difficulty level involved... also James do you live in Washington? Iam over in spokane... we do a lot of riding up north during the summer as well as evans creek area over in seattle area... maybe we could get togather for some rides? anyways your wisdom and help are always appreciated...



  • Shane

Posted January 14, 2001 - 10:45 PM


Hey Clark let me know if your selling your bike... I would like a shot at buying it... my brother is looking for a bike..... and iam sure he would be very happy with your toy! :)


  • hart

Posted January 14, 2001 - 11:18 AM


I have a 98 wr and as per your recommendations, I have ordered the ekn needle. Do I need to do anything with the octopus and air jets to get this thing to act more like the YZ?? Thanks!! your info on this forum has been a real treat!!
Also Clark, how did you get your bike down to 252lb? can you list your changes?


Ion H.

  • James_Dean

Posted January 14, 2001 - 06:04 PM



Take it one step at a time. Just do the EKN needle in clip #3 first. If you get any hesitation try +/- 1/4 turn on the pilot screw and then if needed go to clip #4.

Shane, maybe I should look to you for riding areas around Spokane too. :)


  • Shane

Posted January 15, 2001 - 09:37 AM


Hey James anytime..... we have some great areas to ride over by spokane.... beaty bould up north as well as the pondera rec area real narly in places and you can go for days.... up in the woods.... also st maries idaho rocks as well as cantfield in couer'd alene id....


  • Clark_Mason

Posted January 15, 2001 - 05:41 PM



My WZ420 has many CF parts, Titantium axels, Ti swing arm pivot, Ti linkage and engine mounting bolts, ti bolts in all critical load bearing areas, ti foot pegs and aluminum fastners everywhere else. The CF stuff includes engine mounts, seat mounts, case covers, side panels, fork protectors, CF/kevalar skid plate, etc, etc. Also aftermarket exhausts which knock off a few lbs.

The Bike Stock was 263lbs ready to ride with no fuel in the tank.

Its now at 255-252 depending on which exhaust I run ready to ride without fuel in the tank --but it is now fully dual sported.


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  • John_in_Long_Beach

Posted January 16, 2001 - 07:52 PM


Alright I'm convinced.. I think that I will try the "EK*" series needle.

My last changes where to a DVP needle, and your suggestions were spot on.

Here are my current specs - 2000WR, YZ timing, DVP #4, 180 main, 48 pilot 100 air, DSP tapered header and pipe, box lid removed.

The bike rips. Clark Mason and James Dean hit the nail on the head with the suggestions for the DVP. The bike carburates perfectly with very linear throttle control.

But now I am getting hungry for that midrange hit. I mostly ride 0-5000ft.

Here are my questions to James, Clark or anybody with a similar setup.

1) Which needle would you recommend? EKP or EKN.
2) What is your guess for the main. 170?
3) I should leave my 48 pilot and 100 air alone? Yes?

Thanks in advance your input has saved me quite a few hours testing, and made riding the WR more enjoyable.

John Dumke

  • James_Dean

Posted January 16, 2001 - 09:44 PM


OK!! :D :D :D

#170 main (may want to try #165)
#48 pilot
#100 air
1 turn out on pilot screw

Let us know how it goes! :)


  • John_in_Long_Beach

Posted January 18, 2001 - 03:36 PM



I searched the archives and couldn't find a Yamaha part number for the EKN. I found the EKP (5JG-14916-EP).

Is the EKN then 5JG-14916-EN ?

But then I checked and they listed the PN 5JG-14916-EP as a EVP not a EKP. So needless to say I am somewhat confused.

The EKN is richer in the 1/4 throttle position. Is this better for my setup and less likely to cause a low rpm hesitation, that I read has caused some people difficulty in getting the EKP to work?

Have you had any luck ordering from HLSM, I would like to give them a try as my local dealership is very expensive. They want $20 for a needle.



  • James_Dean

Posted January 18, 2001 - 06:47 PM


You have it correct,

EKN is 5JG-14916-EN

I have not used to buy parts. The 2000 parts fiche is incorrect on the EV* needles, they are EK*.

Yes, the EKN is less likely to hesitate at low speeds. There is a slight difference.

Note:I will be on vacation Jan 20-31 and may not have access to the internet.


  • Guest_Guest_*

Posted January 20, 2001 - 03:41 PM


James Dean,

I'm following your suggestions with the ekp suggest a 165-170 main but I noticed Clark uses a 180+ (with the DVP). Does this pertain to the different needles or different riding elevations? I'm at 4000+'.

  • Parry_in_Clovis

Posted January 20, 2001 - 06:56 PM


Just switched my '01 wr426 timing over to YZ settings and there was no detectable improvement in power. Still pulled super smooth top to bottom, no misses or hesitation. Would that needle change help you think?
If it does, great. If not, I wouldn't suggest anyone changing the timing. Waste of money/effort. It just doesn't make the 426 any better. And I push the bike hard too. I'm former pro mx'r turned dual least that's what I tell people when they ask when I'll start racing again. This bike is pretty amazing (I had a 98 400 YZF and 99 250 YZ before this bike for recent comparisons.)

  • Clark_Mason

Posted January 20, 2001 - 07:44 PM



When running the "E" series needles you will run a leaner main jet. This is due to the steeper taper of the "E" series vs the "D" series needles. When running the "E" serires I will run a 165 to 170 MJ depending on altitude.


  • Steve_Morgan

Posted January 22, 2001 - 11:55 AM


Hi James & Clark:

I just finished 100 miles with an EKP needle in the 3rd clip, with 165 main jet. We rode in the high desert, about 3-4K feet. The bike was noticeably flat throughout the power band. Checked the plug when I got home, it was absolutely bone white!

My original stock needle was in the 3rd clip, and I was running a 172 MJ, which gave me great throttle response and a nice tan plug.

I've now changed the EKP needle to the 4th clip. Will this be enough? Should I also go back to my 172 MJ as well? Also, could I have done any damage to the exhaust valves running so lean all day long?

99' WR400, stock cam timing, GYT-R exhaust, open air box lid.

  • Speeder

Posted January 24, 2001 - 05:30 PM


I ride the high desert as well.
My substantially similar 2000 400,WR timed, with EKP#3 didn't light up until I got to a 180 main jet.
45 pilot, EKP#3, Up-Tite exhaust...
For what it's worth.

  • Shane

Posted January 30, 2001 - 11:20 AM


does anyone have the part number for the #100 air?

my illustrous yamaha dealer does not know what it is.... says there is no option for a 100 air

shane in washington


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