Needle & Jets questions

I just called my local Yamaha shop, Fort Collins Motorsports. I asked what needles and jets they had in stock for a WR426. The guy asked me what type of carburator I have, Mikuni, Keihen, flat or round. At that point, I was a little frustrated and caught off guard at such odd questions. This is similar to a encounter there with a girl in the parts department who didn't know who sold the WR426 and if it was a 4-wheeler or motorcycle and there was one 5 feet behind me that she looks at everyday.

Then the guy proceeds to tell me that they only change the main for this altitude. I let him know that's the reason my bike runs like crap. He then tells me that I'm probably not riding it in a high enough rpm range and that's why I'm fouling plugs. What an idiot!

For the EKP needle, they want $17.99 and they don't have any of the other jets as well. Is this something I have to order from them or can I get if from Sudco? I don't see the needles on their site and I'll do almost anything to buy these parts from someone else. :)


You have the Kehin FCR-39. You can get all the parts you need from Sudco. I found their number, 1-800-998-3529. Check out my thread on plug color, I have some results I put up yesterday. Locally, you can get fuel jets in Loveland or at Tri-City Cycle. Don't know if they have needles.


Hey Steve,

Thanks for the info. I knew what carb I have, I was just irritated that the parts guy at the Yamaha shop is so incompetent. I'll give Sudco a call and get the parts I need.

I did the BK mod on Saturday and was amazed at how much gas was pouring into my cylinder. No wonder the thing is so rich. My needle was in the 4th position (stock) and all they did to jet the bike was replace the main with a 160 and turned the fuel screw out 3 5/8 turns.

I'm still working on all this stuff so I'll take any info you post when I start. I'm still time limited due to the kids so I need all the head start I can get.

John :)

I did the BK mod on Saturday and was amazed at how much gas was pouring into my cylinder. No wonder the thing is so rich. My needle was in the 4th position (stock) and all they did to jet the bike was replace the main with a 160 and turned the fuel screw out 3 5/8 turns.


That is typical. Changing the main jet will help a two stroke quite a bit more than your thumper, where it has considerably less affect IMO.

Also, be careful buying jets. Technically you don't have a Keihin FCR slant 39, that is what comes on pre-2000 YZ/WRs (and KTMs, CRFs etc.). You have the proprietary Yamaha version, called a Keihin flat CR 39. Jetting-wise this is important because the Flat CR uses a "normal" Keihin Pilot Jet (just like a PWK or other two-stroke carb). At your altitude you will probably like a 40 pilot, there are even some Denver TTalkers running a 38 (stock is 42). Also, I was amazed to read your idle mix is over 3 turns out. If that isn't a typo go put it back somewhere between 1.5 and 2 turns before you ride it again.

AlsoII, I only pay around ten bucks for a Yamaha needle from North County Yamaha, 800-225-1629, but they will charge you a shipping/handling fee so it probably won't save you much if all you are ordering is a needle.

Here is my unsolicited jetting advice that I always foist on WR owners:

If you are uncorked & uncovered the YZ needle is a huge improvement.

Here is the Yamaha PN for a stock '01-'02 YZ 426 needle:


Stock clip is # 4 from the top.

I've always thought stock WR jetting was, well, a little weird. But when you consider the sealed airbox, throttle stop, and pinkie-sized exhaust insert it makes a little more sense. If you did that to a YZ it would barely run, and probably promptly foul a plug. So my logic is that as soon as you uncork/unstop/uncover you are riding a YZ from a practical and jetting perspective.

I have jetted two WR 426s for friends, and used the exact same jetting I have in my YZ 426. One of these WRs had YZ cam timing w/ stock uncorked exhaust, the other WR cam timing and a WB R4. The only jetting difference between them was (maybe) a slightly different idle mix.

Hope this helps.


Just responded to your PM. Check it out. I recommend using the jetting setups listed below. Lots of testing put into them, and lots of Taffy (and others) assistance. I'm satisfied that they're just about as good as you can get where we ride...


My bike has the exhaust insert removed, airbox lid off and grey wire disconnected.

The fuel screw setting was not a typo. It was set at 3.625 turns out. I planned on correcting when I get the new jets installed. My local shop is so bad it really bums me out.

I'm a little confused by the needle part number you gave me. I realize it's the Yamaha PN and everyone else is referring to the EKQ, EKP, EMM, EMN needles. What letter reference is the needle you described? I was just about to buy the EKP after reading a post from Taffy.

I'll be careful with the jetting and I'm trying to read as many posts as I can before I do anything.

Hey Larry,

Glad to hear from you. I ride just about everything so the needle is a little bit of a concern for me. I go to Moab in the Spring and would like your jetting there as well.

Most of my riding is from 7000-11,000 feet. I do ride Red Cone/Webster Pass area which is close to 13,000 feet as well. I'd like to be able to stick with one needle setting and live with the fact that the bike is down a little on power above 10,000.



The PN I posted is for an EJP. That is the stock '01/'02 YZ 426 needle.

LarryCo listed two very similar needles that are options on the'00 YZ 426 fiche, they will most likely work even better.


PN: 5JG-14916-EP


PN: 5JG-14916-E1

I'm at 4,500 ft. or so and I run the EKQ on # 3 (40 pilot, 160 main, BK mod etc.)

One thing I always have to warn people about is that when your local parts doofus enters that number the fiche will read "EVP" and "EVQ," substituting the letter "V" for the letter "K" in each case. That is just a three year old typo, those PNs will get you the needles LarryCo is recommending, which I promise will be a vast improvement over your current (stock) settings.

Hope this helps.


If you can get the jets you need locally and just need the needle, send me a note, you can use my EKQ till your new stuff arrives. In my previous post, I meant Loveland Cycle Supply. I know they have the pilots and mains we have been discussing. Ask them if they have the air jets also, but if you order from Sudco, get the pilot air screw, it is adjustable for many settings.

Good Luck,


Thanks guys.

Hick I guarantee that my local parts doofus is dumber than yours so even if I explain it to them, I'll still get the wrong parts. I'll order them elsewhere. Thanks for the needle lesson. At least now, I can look on Sudco's site and understand what you guys are doing.

Steve, I'm all apart right now and can't ride for a couple of weeks anyway. If I can't get the needle, I'll call you and borrow yours till I can get it.


Hick I guarantee that my local parts doofus is dumber than yours...

Is that a challenge? If so I offer this paraphrased, yet actual conversation that took place between myself and the parts guy at Mr. Motorcycle (affectionately referred to as Mr. Moron-o-cycle locally):

Me: "Ya, I need a chain for my dirt bike."

Parts: "What kind of bike is it?"

Me (sensing trouble): "It is a YZ 426."

Parts: "Is that a Honda?"

Me (going into full-safe mode): "Uhh, yeah!"

Parts guy disappears into parts land, returns two minutes later: "Sorry, the closest thing I have is a 520. Will that work on a 426?"

Me: "I think I can make it fit."

Top that. :)

You should feel lucky the chain was in stock. The only thing my dealer has ever had in stock is a spark plug.

Right after I bought my WR426, the gas tank strap went away (after changing a damn plug!) so I go to the local Yamaha shop to get the part.

Me: I need a gas tank strap for a 2001 WR426FN.

DS from parts: Who Makes that?

Me: Yamaha

DS from parts: Is it an atv or a motorcycle?

Me: Motorcycle

DS from Parts: What displacement?

Me: 426cc

I finally had to look on the microfiche and point to the part for her to order it.

The thing that really pissed me off is the same bike was 5 feet behind me on the showroom floor. She looks at the thing everyday and still doesn't have a clue what I'm talking about.

I received an e-mail from the shop letting me know they were having a sale and I sent them one back telling them to take me off their e-mail list because they were incompetent morons and I'd rather drive to Denver or mail order parts than buy another thing from their shop. The parts manager, a girl who is pretty damn bright, calls me and tells me she'll give me a $25 gift cert. if I come in and discuss it with her. So I do and get my certificate.

Next trip I need a battery for my Vmax.

Me: I need a battery for a 1994 Yamaha Vmax street bike.

DS in Parts: What's the displacement?Me: irrate at this point. I bought $25 worth of oil and left.


I called Sudco and they didn't have the needles in stock. I guess these are only sold at Yamaha dealers. He also didn't have the 38 pj.

I called Twin Peaks Yamaha, which is South of me and actually talked to a competent parts guy. They ordered me a EKP needle, and had the 38 PJ and the remaining Main jet I was looking for, in stock. That was a nice change.

After I get all this stuff installed, I'll probably need more help.

Thanks again guys for getting me this far.

The only thing my dealer has ever had in stock is a spark plug.

That tempts me to relate my NGK story, though my point has already been made. Long story short is the parts guy didn't know what NGK was. I was dumbfounded to the point of actual, physical and mental paralysis. After a few minutes of stunned silence I recovered, stepped behind the counter and got it myself.

They always want to follow this involved invoicing procedure, starting with them asking for my phone number etc., I wasn’t in the mood for that so I left five bucks on the counter and walked out. That was my last trip to the parts counter at Mr. Motorcycle. Thank God.

My riding buddy bought 4 new plugs for his street bike. Got home, opened the boxes to install them and guess what he found? One was hotter than what he wanted, 1 was physically larger and 2 were used, old plugs. All sold to him in the correct boxes. He took them back and all they did was give him new ones. Didn't say sorry, didn't give any excuse, nothing, just told him "don't know how that happened."

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