2001 WR 426 jetting at altitude help

Hello out there, I have my carburator apart at the moment for general cleaning and to see what the jetting was set at (recently bought and came from colorado originally) since I don't seem to have the best performance. My WR 426 2001 bogs and sputters a little mostly in the 1/4 to 3/4 area and backfires when coming off the throttle. Grey wire mod and air box lid removed for mods. Looks like I have the following:

main jet: 178 (way rich I think, stock is 165)

pilot jet: 45 (stock is 42)

jet needle clip is at 3 (stock is 4)

everything else is stock I think

I ride in Utah and will be primarily in the 6000- 9000 altitudes where I want the most performance, low humidity generally and hot in the valley but cool in mtns at altitude. Any advice from anyone out there riding in similar climate or area. Thanks for the help and I will continue searching old threads for some help, thanks from the newbie,

It sounds like your Main is way too rich and may be overlapping some of the other circuits. That's where I'd start if I were you. Drop it down to the stock 165 and see what happens. You may also need to experiment with the fuel screw. 1.5 turns out usually is a good starting point. Get back to us with the results...SC

hey welcome to TT.. :D where in utah are you at? I live in south ogden, and I am always up for a ride... there is a 40+mile single track that goes from pineview to benlomond peak.. :D pm me if you are interested....

I run 162/40... needle 2nd position. Works well at that altitude here in Idaho.

main jet: 178 (way rich I think, stock is 165)

This site has a jetting chart under "tech articles" and from what it shows 178 is way too rich.


Thanks for the Info, I just got the carb back together w/ a 162 main and 40 pilot, pilot screw 1 3/4 out and needle clip in 3rd position. Runs much better, no bogging through out gears and no backfiring on deceleration anymore. I wants to pull the front end a little better but I'm still not wheelieing like I'd like to be, what gears are you all able to pull up your front end? thanks for your help, jon

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