Anyone tried the JD kit for a 426 yet?

29 replies to this topic
  • HollandWR426

Posted July 11, 2003 - 08:35 AM


Just checking to see some results. I am particularly interested in someone with a nearly stock bike except some of the free mods and maybe a baja designs baffle. Want to see if anyone thinks it is worth the cash. :)

  • dominator426

Posted July 11, 2003 - 03:40 PM


It would surely be good for the unexperienced and would also allow various settings for different states of tune, elevation and temperature ranges...

  • blue_beast_wins

Posted July 12, 2003 - 03:05 AM


I'd be happy to test it for free, but i aint payin for it, sorry.

  • James_Dean

Posted July 12, 2003 - 06:51 AM


I put the kit on a WR426 2 months ago. The bike had nothing but the free mods. I used his comments in choosing the settings from sea level to 6000ft elevation.

Mike, Give us some FEEDBACK HERE! You owe me :)


  • tctrailrider

Posted July 12, 2003 - 10:42 AM


Blue Beast,
For all JD and others have done for jetting, I'd be happy to send $65.00. The jets would be a bonus. Without the help from the pioneers my bike would run like crap, and I would be afraid to touch it. I have at least $100.00 worth or jets on the bench. To get jets and instructions for $65.00 is a steal.
JD, hats off to you. In the spirit of American Capilalism you have found a way to make a buck (I hope). To take your years of knowledge and experience, create special needles and have the courage to take it to market is great. I will order a set and if Taffy invents something I will buy that too. $65.00 is cheap.

  • captain_S

Posted July 13, 2003 - 01:13 PM


tctrailrider, Now there`s a guy who knows!,yamaha have already quoted a few names from TT on their web site!,good on ya guys :),i hope james dean will reap the rewards he is due,and the other guys that try so hard!,excellent work i think :D

  • basicblues

Posted July 13, 2003 - 02:55 PM


If someone is willing to spend several thousand $$$ on a bike and outfit it with a few aftermarket parts and are not willing to spend as little as $65 on a proven winner like the JD jet kit. I think you need to reevaluate. Not only would the performance gains be worth the price but the tons of time saved experimenting and removing the carb and reinstalling it 20 or 30 times would certainly be worth the price. Most of us may have a general understanding of jetting but probably most of us don't understand the technical aspect of jetting, we just want to ride. If you have been to your local motorcycle dealership lately and asked about jets, you may find they just don't carry them in stock anymore, special order only... I been told by Yamaha and Honda both that they do not plan to carry an assortment of jets anymore because they claim there are just too many various jet sizes to stock for every motorcycle they manufacture. Go to the local dealership and try to buy yourself a handful of jets and needles, you still won't have the type of needle James Dean produces and you could spend weeks trying to get your bike run right. We should be grateful that James spends time helping us dial in these jet kits. :) How much is a jetting expert worth to you? More than $65? It's worth it and it's a bargain...

  • BlueThunder

Posted July 13, 2003 - 08:39 PM


Besides that, have you asked the garden variety tech about jetting your ride lately. Most of them clowns are set-up techs or specialize in oil changes and valve adjustments. No offense to any tech reading this that is proficient but you know what I'm talking about!
1994 MMI graduate w/ honors from Theory to Advanced 2&4 Stroke Performance clinics....took it just for fun, so I'm not just talking outta my :D, and I'm still confused by jetting on occasion! Props to James for helping out the masses with some hard work, dedication and know-how :)

  • Wicked_Crash

Posted July 14, 2003 - 04:45 AM


I just installed the JD kit in my 426 on Saturday. I was a little sceptical going from a 148MJ to a 160MJ at my elevation, but am amazed at the results. My old jetting settings with the EKQ needle worked great and I didn't think it could get any better. After installing the JD kit, my 426 is even more of a powerhouse. I can easily wheelie in third gear, even when I'm far forward on the seat, and fourth gear wheelies are easy too with just a little pull. My new JD settings are posted along with my old settings in my signiture. Thanks James for making such a great kit. :)

  • LarryCO

Posted July 15, 2003 - 01:31 PM


OK've peaked my interest here as well. :)

Would you mind describing your "red needle" and comparing it to say the EKP? If I understand correctly, it's a multi-tapered needle (is this even correct??)...and if so, what taper angles is the needle comprised of? What's the comparable code for the needle straight diameter?

I'm always looking to learn something if it's not "sensitive info", please respond (or drop me a PM) when you have time.

Larry (used to be CO).

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • James_Dean

Posted July 16, 2003 - 10:35 AM



They are both triple tapered needles in the kit.

Without giving too much away, the needles (red & blue marked) are richer and leaner than EKP on the diameters. The red is leaner for hotter/higher/humid conditions. The blue is richer for colder/lower/dry condition. The red (#4) needle will run similar to EKQ#2 in the lower range, except there is a transition taper to avoid the lean 1/8-1/4 throttle range. (Avoids the weaknesses keeps the strengths)
The top end, 3rd taper, transitions to also allow the use of bigger main jets.

The 2-strokes have used triple taper needles for 15 years. Mikuni started with double tapered needles in the 70's, and then triple tapered in the 80's. At my request, Mikuni America sent me charts with all of the available needles graphed on paper. This was 20 years ago and I've been charting the new developments ever since. It took a long time for the manufacturers to get jetting to work this good.


  • LarryCO

Posted July 16, 2003 - 11:28 AM


Thanks for the info! Pretty neat stuff...I suppose one of these days I'll have to get my hands on one of these and check it out firsthand...

I suppose you've also updated your JD jetting excel spreadsheet to be able to support both the standard single taper needles as well as your new triple taper beauts...

Again, thanks for the reply...nice job!

Larry "used to be CO"

  • tctrailrider

Posted July 17, 2003 - 02:16 PM


Ordered the JD kit from TT late Monday, arrived Thursday. I have tried about 50 jetting combos to end up where I have, EMP3, 160MJ, 160MAJ, 38PJ, 60PAS. Just above sea level instructions call for stock settings, 42PJ an 165MJ with Blue needle 4. I knew this would be rich all through it but followed the plan. To my surprise this is a very good setup. Very clean all through it. Very happy with previous jetting but this has more hit around 1/8 to 1/4 throttle. This is a very different needle, the tip is about the same as a DRR so you need a larger main than the normal E taper. I will do tests with different PJ, and MJ but this out of the package setup is very good. It took me about 50 different jetting combo's to be happy and this one was first try. Thanks, JD.

  • James_Dean

Posted July 18, 2003 - 05:32 PM



I'm glad you like the jetting kit. We have something in common with testing needle combinations. It took many more than 50 test runs to come up with the needle profiles. Much of it came from listening to others here. It's fun to see test runs make improvement, and getting to share it is gratifying.


  • larsonsenza

Posted July 19, 2003 - 05:16 PM


Did you put the 200 maj back in with JD jetting or leave the 160 maj in there. Keep us posted on PJ testing with JD jetting. Thanks

  • tctrailrider

Posted July 20, 2003 - 07:52 AM


Went back to all stock. PJ42, PAS75, MJ165, MAJ200, fuel screw 1.5 with JD Blue 4. Later today I plan on a little testing. I get one or two bangs on decel from high RPM other than that its great. The acceleration from 1/8 to 1/4 is much better than all other tries.

  • tctrailrider

Posted July 20, 2003 - 10:42 AM


More testing today, ended up with jetting in my signature. Very responsive, no pops, bangs or other issues, starts great. I don't have the equipment to accurately measure and compare but this is a different needle. The tip is wide like a D taper so you need a larger main. Something is different at the end of the straight or beginning of the taper. The change from 1/8 to 1/4 throttle is very good, real strong. Other setups had a very small flat spot there. JD will sell alot of these.

  • larsonsenza

Posted July 20, 2003 - 03:10 PM


Thanks for the info. I ordered my JD kit today. I will not get up north probably for another two weeks to be able to try. How is the mid to top end with this set up? I see that you went up to the 168mj, did you try a 170 also? Did the ps at 1.75 cure the pop on decel or the larger mj? Your information has been very helpful.

  • tctrailrider

Posted July 21, 2003 - 03:15 PM


1 3/4 on the fuel screw got rid of the bang on decel. I then took out the PAS and installed the stock 75PJ and this worked very well. No bangs and seemed cleaner on accel. with the FS at 1.5. From bottom to over 3/4 is great, some missing above that. Tonight worked hard on MJ. From 160 to 170, also changing MAJ from 200 to 160. Haven't been able to work out the miss. The next day or two I will test the 172 and 175MJ and see what happens. Its close but not perfect.

  • gratefuldawg

Posted July 21, 2003 - 03:18 PM


Bought the JD kit last Tuesday and got it on Thursday. Dropped it in and went riding all weekend. My WR is uncorked, lid removed and otherwise stock. I was riding 9000 ft+. Tried the JD suggested combo, red needle #3, 160mj and stock everything else. First test I was disappointed, sputtering, popping etc. Dropped the red needle to #1 and bingo!!! This is what I have been waiting for. Crisp smooth power delivery, wheelies in 3rd. Where was JD 5 months ago. I had tried some of the other jetting suggestion LarryCo, now LarryMN and Taffy, but they just did not work on my particular bike, thanks guys I still really appreciate your help. I will try the suggested JD jetting at 8000-10,000 and this fall at Moab 4000-6000 and report back. Bottom line for me is it was well worth the 65 bucks for a jetting newbie. I just wish the JD kit was available a few months earlier, I would have saved a few bucks and a lot of brain damage. My 2 cents. By the way I have an EKP needle for sale, cheap.


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