2002 wr426f question

This question has probably been asked thousands of times, but i keep getting many different answers. The bike is completely stock with these free mods. Cut Grey wire, set throttle stop to allow for full throttle, removed baffle, and removed air box lid to allow more air. The bike runs good but sometimes when i hit the throttle it bogs down bad. I was just wondering what the best jet set up would be, thanks alot!

what's your elevation?

i believe around about 300' above sea level, thanks for the help

start with a #50 idle jet. Make sure your mixture screw is set right. And for more advanced info on the accelerator pump, refer here.

This is my bike, it is an 01, but is identical to the 02:

Year: 2001

Model (400 - 426 - 450): Yamaha WR 426

Cam Timing (WR/YZ): WR timed

Main jet: 168

Pilot Jet: 45 (or 48, I don't actually remember)

PAJ: 100

Leak Jet: NA

Starter Jet: 65

Fuel screw (turns out): 2 turns out

Needle Model/Clip position: JD Red #4

Grey Wire Mod (Y/N): Yes

TPS Connected (Y/N): Yes (not re-adjusted from factory)

Airbox Snorkel/Lid (on or off): Airbox lid off

AIS Removed (Y/N): NA

Airfilter Brand: Twin Air w/ No-Toil Oil

Exhaust Brand: FMF Q

Average Altitude: 700ft (Michigan)

Average Temperature: 70-90 F

Average Humidity: 70-90%

Degree of Satisfaction (0-10): 9 (we can always want more can't we?)

Additional Mods/Comments: Additional mods:

Light Blue Wire

O-Ring Mod

ACV disabled (which is why I have a 100 PAJ rather than a 75 stock)

YZ throttle stop

This is the list of my bike settings/mods. I had the same settings using the stock exhaust can with they GYT-R tip. The combination of a new exhaust and O-ring mod were the 2 most dramatic thing done. It cleaned up the low end bog, and unleashed a lot of extra power, especially down low. I did the BK mod to the carb and personally found that the O-ring mod was far superior, so I no longer have the BK. The carb should still be tuned such that the spray of gas just misses the slide. I MAY have gone from a 45 to a 48 pilot when I went from the GYT-R tip to the FMF Q pipe.

I used to have the dreaded bog down low, but properly jetted you can basically tune it away.

what's the O-ring mod?

The O-ring mod rocks. I had noticed my AP was working poorly and was wondering how to fix it. This mod is exactly what I needed. Bog is now gone. I owe you a beer.

Good to hear:thumbsup: That mod was far and away the best I had ever done for performance.

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