James Dean Jetting Kit Now Available For WR400/426/450

I just did a post on jetting for the Colorado 500, I'm wondering what jetting I'm going to need to ride above 8000 feet. I'm from White Salmon, WA :excuseme:and the stock jetting works pretty good riding MT. Adams trails to 5000 feet.

If you're asking about the jetting kit, instructions are included for riding above 9000ft elevation. The kit was tested in Colorado up to and above 12500ft elevation.

Stock jetting needs the clip position moved leaner and smaller main jet by 1-3 steps, depending on model.


I have a 99 WR 400 with YZ cam timing and stock pipe with Baja Design insert. I usually ride baja at elevations of 3000 to 5500 feet. I currently have a 48PJ, DVP needle#4 groove, Pilot screw 1 1/4 turns out, 170 main jet. After my engine was rebuilt recently, the bike starts ok but hesitates at midrange, and is very strong mid to top. Any ideas would be appreciated.

I noticed the TT store says there's (for the moment) no shipping outside the USA, suppose my very loving girlfriend, knowing how much I want the JD kit, were to need it shipped to Canada? Maybe even in a hurry for and October B-Day? I mean, I know Canada's not the US, but is there really no way?

There is shipping outside the US. Contact thumpertalk for shipping information. They are very helpful and quick.


Thanks, got it ordered this morning, but shipped to family in the US and they'll send it on up. So, the next move is for me to muff it and then come back here for help cleaning up my mess :)

Very expensive for 2 needles and 4 main jets. I already had the mains, just need the needles. I'm sending mine back and ordering the needles.

You cant get just the needles, it comes as a kit. IMO its a very reasonable price for what you get in return. For how much research and development went into this kit, it could be $150 and still worth it.

There is shipping outside the US. Contact thumpertalk for shipping information. They are very helpful and quick.


Unfortunately TT is not accepting my Credit Card, becouse I'm born in Bulgaria and I have bulgarian credit card. Yes I know there are other way to pay, but they are all very expensive and I cannot aford them. I loved TT before this, and now I feel my place is not here... maybe I must only read my Bulgarian forums huh! :)

Im sure they can help you out in some way. Do you have paypal? If so I or someone else here can order it and then drop ship it to you? Hope this helps???

Thanks for the help, but I do not have paypal for the same reason...

I can use some friends credit card isued in another country, but why it has to be that way. After all they have to make things easy for customes...

I have no problem shoping in Amazon, ZipTy Racing, NavTechGPS, Scotts performance, Guts Racing, MotoWorld Racing, Cycra Racing and much more... Some of them called the bank to make sure I'm the owner of the card, but I guess TT finansion department, or the bank they use prefere to deny my order...

Anyway thanks for trying to help!

Get the kit and do the BK mod and you should be good to go. :)

I would like to know what the BK mod is? I'm going to order a JD kit in addition I have an 01 WR426FN with a flat spot on accel also.

Do the wr426 kits come with a set mainjet or do you have to specify what sizes ?

Looking for Advise-

I just purchased the James Dean Kit for my 2003 WR450f. I will be installing the kit this weekend. What needle & jet do you recommend for my bike, I am assuming that I use the blue needle and 170 jet as the instructions suggest?

I live in Lower Michigan and ride the street and trails during the spring, summer, and fall. No winter riding. We don't have a humidity problem, summer temps usually between 50 to 80 degrees I have the following modifications done to my bike:

Yoshimura RS3 Comp full Exhaust system (header & cannister), YZ Throttle stop, Grey wire cut, Air baffle removed, & Uni twin air filters.

I always run 93 octane, should I continue? Any other suggestions?

When I ran the stock exhaust system with removed baffle, exhaust cork, and grey wire cut, the bike ran well but alot of "popping" on decelaration. It always felt like the bike had more power to offer. I have not ran the bike yet with the Yosh RS3 Comp exhaust.

I installed the James Dean kit, and am very happy with the results. Crisp response, no backfire, excellent start up. The kit is worth the money, and installation was less than 1 hour. I am running the blue needle with 170 jet.

I live at 8150 feet and ride 8150+ up to 10500 feet. Will the JD Jetting Kit give me the jets I need jet my bike for these elevations? I ride a 03WR450. Most of the other riders in this forum are riding at 0-5000 ft. But since I ride at higher elevations, I am assuming I would need smaller jets. Is there a kit that would be useful for me?

I live and ride in Michigan. At 60, I have started to transition to dual sport. I now ride a 1997 WR250 (2-stroke). I expect to pick up my 2004 WR450 next week. I plan to install the GYT exhaust insert, cut the gray wire, install the YZ throttle stop, and remove the air box lid. I may also install the James Dean jetting kit. What groove did you use on the blue needle? Could you tell a difference with the James Dean kit. It has taken me two years to get my WR250 jetting correctly.

Dear redwoods,

What does the ZIP-TY fuel screw do for your bike?


I am pretty new to the jetting scene. I do know that, once I get it all put together and running, the zip-ty fuel screw is used for minor adjustments to your carb to get a snappy throttle response. Once you have it dialed in, you can use the screw, which is external and easily adjustable, to make minor adjustments when you go up or down in elevation or if other factors like temp or humidity change and create a need for fuel/air adjustment in your carb.

Hope this helps. Other readers: feel free to correct me if I am wrong.

I've just ordered the JD kit for my 00 WR.

Can you give me a baseline for my bike with a james-now and FMF Ti pipe?


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