01 Wr426f Jetting Help

Hello everybody, got a nice 01 wr426 that had stock exhaust and jetting. Got a great deal on a full pro circuit system for my bike and wondered if anyone else here has done this and if so what jetting did you change to? Thank you for any advice.

You should tune your accelerator pump circut first as this will affect the jetting. BK mod,O-ring mod, Heavy Accelerator spring, The choice is up to you and everyone here has an opinion on how you should do it. Then use the YZ needle from the same year or the JD jet kit if you prefer. You spend more money on the JD kit but they give you instructions and support.

There is a jetting data base at the top of the forum where you could pick and set up for a similar altitude and weather pattern for your location. Depending on what you do to your AP circut will affect the jets you end up with

I have my information listed in the WR jetting database, and I still ride the 01WR426 in Michigan. I probably ride in similar conditions for elevation and temperature.

I do not have a full exhaust, but just the FMF Q slip-on with stock header. I did have to go up a size on the pilot jet as the bike could flow more air. I also have done all the free mods, including opening up the airbox. I tried both the BK mod and the O-ring mod, and found that the O-ring mod works much, much better.

Make sure you do the free mods to wake up the beast within: Airbox top removal, throttle stop, grey wire, light blue wire, O-ring, ACV disable, chain slider fix, JD jetting. That's all I remember off the top of my head.

Hello everybody, got a nice 01 wr426 that had stock exhaust and jetting. Got a great deal on a full pro circuit system for my bike and wondered if anyone else here has done this and if so what jetting did you change to? Thank you for any advice.

I had the same bike and setup years ago. I really miss that bike. I had it dialed.... :ride:

Sea Level:

main - 168

pilot - 48

clip pos - middle

3000' and higher:

main - 165

pilot - 45

clip pos - middle

Both setups requre the fuel screw about 1.5-1.75 turns out.

Thanks to everyone who replied. Sorry it took me so long to get back on here. Really appreciate the info. this site rocks!!!

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