Jetting for '02 WR426

I have a '02 WR426 with the following mods:

Air cleaner lid gone, baffle out, BK mod, ACV mod,

150MJ, 38PJ, 160MAJ, 65PAJ(bought the Sudco adj screw-3/8 turns out),

EKP #3.

The bike is strong low to mid rpm's, the problem is if you are going

slow in first gear say 5-10 mph, then nail it and hold the throttle wide

open, there is hesitation & surging & coughing in the upper rpm's in second

and third gear.

We ride mostly in the 5,500-7,500 foot elevation.

The manual doesn't talk about the Main Air Jet or

Pilot Air Jet...if I go to a higher Main Air Jet will

this cure the surging/hesitation in the upper rpm band?

Any suggestions or possible solutions are greatly appreciated.

Try a 160 mj.

I agree, it sounds lean on the main jet.

I ride at around 4,000 ft., 40 pilot, 160 main, EKP-3, 200 MAJ, ~85 PAJ.

The air jets have a more pronounced affect the higher the rpms, but I'm still inclined to believe your main is a tad on the small side.

Try two sizes richer on the main, you should be able to notice some difference in the area where you are having the problem and then you will know if you are on the right track.

Hope this helps.


I run a 155-160MJ when riding around town or at Rampart. Save that 150MJ (or even a 148MJ) for use over 9K in Crested Butte or Idaho Springs...

You should be able to go a bit richer than normal due to winter and the colder air...

LOL...forget my sig below...need to update that to reflect the correct MJ's! :)


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