Raise needle?

15 replies to this topic
  • Mxer303

Posted January 31, 2001 - 11:00 AM


I just installed a 45 pilot and a 165 main in my 00 426, and was wondering if I also need to raise the needle?(live in Ky)

  • Taffy

Posted January 31, 2001 - 11:51 AM


i have no answer for you but Taffy has another hunch (watch out everybody!)& i'm hoping you'll take the time to help me.

did your bike have a 42 pilot in it?

if it did, what is your pilot airjet size please. if you look at the entrance to your carb you will see a slit at 7 o' clock in which are two jets. one is probably 200 tthe other may be 100 or smaller. thanks in anticipation.


  • Mxer303

Posted January 31, 2001 - 09:32 PM


I had a 42 pilot and 162 main to begin with. I was trying to get rid of the hesitation and did not know if needle position affected this.

  • Taffy

Posted January 31, 2001 - 09:34 PM


so 303 can you tell me sometime soon what your airjet size is?


  • Hick

Posted February 01, 2001 - 07:06 AM


My '00 YZ has a 100 pilot air jet, the WR has a 75. I don't know about '01, but I think these are the only two sizes that Yamaha has used.

  • Taffy

Posted February 01, 2001 - 08:51 AM


help me here hick if you could please.

when yam fitted a 42 what was the PAJ?
when yam have fitted a 45 what was the PAJ?

i need this for the last three years on both models.


  • Hick

Posted February 01, 2001 - 01:37 PM


All US YZFs list 100 air as only PAJ size.
All US WRs list 75 air as only PAJ size.

’98 & ’99 175/45/DKR
’00 162/42/EKR
’01 162/42/EJP

’98 & ’99 168/45/DTM
’00 165/45/DRS
’01 165/42/DRR

YZ400 had “D” needle, very big main, and big pilot.
WRs have “D” needles, big mains, bigger pilots and smaller APJ.
YZ426 got “E” needle, much smaller main and smaller pilot.

What does all this mean? I have no idea, but the big main seems to go with the “D” needles, the larger displacement seems to want a smaller pilot and the WR, no matter the displacement, always gets the smaller PAJ.

Emissions considerations and equipment? I’ve never even seen a WR up close but maybe part of the “de-octopussing” those guys are always talking about should be a swap to the 100 APJ.

Are Euro models jetted significantly different? Did your WR have any emissions add-ons (octopus)?

  • James_Dean

Posted February 01, 2001 - 05:15 PM


Looks like the WR always gets the #75 and the YZ always gets the #100 pilot air. Probably for the idle and cam timing on each.

The E-- needles need smaller mains.
The '00 and '01 WR's have smaller mains, but this is when they were also sold in California, unlike the '98/'99 models.

The FCR2 on the '00 and '01 use #42 pilots
The FCR (original) on the '98 and '99 use the #45

Note that all KTM's (FCR) are using #48 pilot and #100 pilot air jets. They only use 3/4 - 1 1/2 turns out on the pilot screw and have the DTM needle.

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  • Mxer303

Posted February 01, 2001 - 09:38 PM


How will I be able to tell if the needle needs adjusting?

  • Hick

Posted February 02, 2001 - 08:19 AM



The needle probably has more effect than any other jetting change. Mixture from 1/8 throttle to (almost) WO is controlled by the needle. That is a wide range, but you can break it down to smaller components of that range and determine if you should try a new needle or just a different clip position.

PNs with three letters describe the needle, up the alphabet (towards Z) is leaner, down (towards A) is richer (they skip the letter O & I, to avoid confusion with zero & one I imagine). First letter is taper, second is length (between top clip and start of taper), third is diameter of the straight portion of the needle (above where the taper begins). The second letter is equivalent to clip position (counted from the top, higher clip # is richer). Changing the second letter by two is equivalent to one clip change (i.e. EKR #4 = EMR #3).

Check out Carb Parts Needle Jet Changes page. Look at the chart for 35-41mm carbs (YZ/WR have 39mm). The chart indicates that the third letter governs 1/8 to ½ throttle, the first letter ½ to WO. So if you are too lean at 1/8 throttle, try going down (towards A) on the last letter (i.e. stock ’00 YZF is EKR, try an EKQ, EKP, EKN etc.)

As for clip position (or middle letter), this changes when the carb comes onto the taper, so I guess if you are good at 1/8, then too lean just after, then good again beyond ½ you need to raise the needle (higher clip #).

I have an ’00 also and ride at 4,000 ft. with 162/45/EKP #4. Since you are probably at much lower elevations I’m guessing you would benefit from trying the EKP or EKN. Yamaha would agree since for ’01 they changed the needle to EJP (almost identical to my EKP).

How am I doing JD?

Keihin Needle Jet Tuning
Prof. James Dean
Thumpertalk Rm. # WR
MWF 9:00-12:00
(this course has web-based open enrollment and can be taken on a self-evaluation, pass/fail basis). :)

[This message has been edited by Hick (edited 02-02-2001).]

  • Mxer303

Posted February 02, 2001 - 09:06 PM


Thanks for the info-jetting on the 4-stroke seems to be a little more complicated to me. It seems like it was easier to figure it out on a 2 stroke.

  • Taffy

Posted February 03, 2001 - 12:23 AM



sometimes you say the middle suffix is to the taper, then you say it's to a point 2.515 (or somthing!). what is it?

hick, how do you do that 'click here' to see thingy!


  • James_Dean

Posted February 03, 2001 - 03:46 PM



Referring to the second letter and taper starting point-

You had a near perfect score until Taffy jumped in. Taffy gets extra credit. If all needles had a straight diameter of 2.515mm, the statements would be right. (Hick knows this, but was trying to simplify)

Sorry, Minus 1/2 for the taper start matching the L1 length or even matching the change in L1. :D

The L1 is measured to mid-taper at 2.515mm. The taper starts a little higher on a DVR(2.755mm) than a DVP(2.735mm), and higher yet than DVM(2.715mm). These needles appear to have their tapers and clip positions machined first. So all DV- needles looked the same until the straight diameters are machined. A smaller straight diameter makes the taper start lower for an identical L1 and taper. All the DV- needles have EXACTLY the same jetting after the taper crests the needle jet (nozzle).

This is why the EVP needle has nowhere near the same taper start of the DVP. (Hick already knew that) So EKP or EMP are the closest to starting their taper at the same point as DVP.

An unusual example: There are a few Keihin needles with smaller straight diameters than 2.515 (i.e. 2.45). The L1 measures to somewhere along the straight diameter. This is where the needle taper was before the straight diameter was machined and took it off. :)

James ("The Dean") :D

See Below -

Posted Image

[This message has been edited by James Dean (edited 02-03-2001).]

  • Taffy

Posted February 04, 2001 - 11:38 AM


thanks jd. there are no flies on hick so no worries.

so how do you click HERE hick?

jd i've posed a question to bk on the CF airbox thread.


  • Hick

Posted February 05, 2001 - 07:38 AM



When you post, note the link just to the left of the box where your thoughts go, it is labeled *UBB Code is ON. This links to a page that explains the things you can do with the Ultimate Bulletin Board commands. The first topic is entitled “UBB Hyperlinking” and outlines how to put a link in a post.

Also, you can easily click the “Edit/Delete Message” icon: Posted Image from any message where a link is used or a picture posted and view the raw text, including “UBB commands” that the poster used. I could try to put the actual text of the commands and how to use them but I forgot how to make the board ignore the commands and display them instead.

BTW I used the “” and “” commands in this post and just learned that you cannot “nest” the image command in a link. So I’m still figuring this out.

Hope this helps.


I wasn’t sure about the 2.515 or the reasoning behind it so I left that part out. Your comment about the taper being machined before the straight diameter made it clear. Thanks for the correction/clarification/explanation. :)

[This message has been edited by Hick (edited 02-05-2001).]

  • Tom_Higdon

Posted February 05, 2001 - 08:23 AM


Just picked up and installed the EJQ (# 5JG-14916-J1) needle for my 01 426 that has been on back order the last few weeks. Man, I just THOUGHT it was running good before! Now, it hits so hard coming out of corners I have had to order a gripper seat cover. The plugs are almost perfect looking too! (168 main, stock pilot 2 1/4 turns out, 3000 ft 50-60 degrees.)

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