WR426 JD kit jetting help please James Dean

I’ve done a search but can’t find what I’m looking for. I have a 2001 WR426 with a YZ426 exhaust, YZ timed, air box lid removed, YZ throttle stop, and grey wire unplugged. I installed the JD kit as directed but can’t seem to get the bike to rev out like I think it should. I started with the 170 main jet and then went down to a 168 but it didn’t seem to help it at all on the top end but the midrange seems effected when I changed down to the 168. I ride around 1500 feet above sea level in east TN. Should I go even smaller with the main jet?!?!

I'd go with the 170 if you never go higher than 1500 ft. I have the same setup except for the yz timing (haven't tried that out yet) and I run a 170 from sea level to over 3500 ft. with no problems. I also put in a 42 pilot jet (I think that's what it was, 1 size bigger than stock whatever that is) and I used both needles that came with the kit and didn't feel any difference between the two. S I chose to go with the red with the clip in the middle position. Runs great.

Year: 2002

Model (400 - 426 - 450): WR426F

Cam Timing (WR/YZ): WR

Main jet: 170

Pilot Jet: 45

PAJ: 75 stock

MAJ: 200 stock

Leak Jet: NA

Starter Jet: 65 stock

Fuel screw (turns out): 1.5

Needle Model/Clip position: Blue JD needle 3rd position

Grey Wire Mod (Y/N): Y

TPS Connected (Y/N): Y adjusted to specs

Airbox Snorkel/Lid (on or off): off

AIS Removed (Y/N): NA

Airfilter Brand: UNI

Exhaust Brand: WB E2

Average Altitude: 0-1000

Average Temperature: 60

Average Humidity: 80

Degree of Satisfaction (0-10): 10

Additional Mods/Comments: Thin JD O-ring used on accel. pump linkage

Lots of low-end grunt and power everywhere on the RPM range.

No more hesitation or missfiring at cruising speed (TPS adjustment fixed that)

___________________

This is my setup and it works great from 0-1000ft.

You should be ok with the 170 main

Other things to check

TPS adjusted correctly

Float level

Spark plug gap

Valve clearance

It also helps to periodically remove all of the jets and flush out the carb (both fuel and air passages) with carb cleaner and then compressed air.

thanks for the replies guys! but keep them comming! i was hoping James Dean would chime in sometime also. i tried it out again last night by adjusting the fuel screw and got it a little better throttle responce i think. the bike is in tip top shape so the only thing it can be is jetting as far as i know.

thanks for the replies guys! but keep them comming! i was hoping James Dean would chime in sometime also. i tried it out again last night by adjusting the fuel screw and got it a little better throttle responce i think. the bike is in tip top shape so the only thing it can be is jetting as far as i know.

PM James directly. This is a huge site and to expect him to peruse all the threads is asking for a bit much, don't you think? He has ALWAYS replied to my PMs within a day or two.

Your thread has been copied to the Jetting forum. You'll likely get JD to answer directly...SC

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now