Please help my 426 is ill

Hi all! I could use some help. I have been looking at the jetting post for a few weeks now to try to make my 426 run acceptable. All I am looking for is smooth throttle. Peak performance would be a plus.

What I have: A 2002 Canadian WR426, Airbox lid removed, WB E series pipe w/6 discs an USFS arrestor. Stock jetting for now. I live at sea level but will run at 3000-6000 depending on where I go.

The problem: Holding the throttle steady anywhere from 1/8 to 3/4 it surges real bad, worse inlower gears, like its running out of gas. If I blip the throttle it clears up and accelerats but will surge again at steady throttle. This seamed lean to me.

What I have tried: I installed a WB E series pipe, no change except for noise. I installed a new plug, old was clean and off white in color. I tried the fuel screw in to 1 1/2 turns then out to 3 1/2 with no change in symptom. I tried a 1 step leaner main an 1 step richer main, no change in the surge. I read the posts about the EMM needle and I just got it today and will try it but when I raised the stock OBDQR needle (richer mid) to clip 7 it got worse. I may try the needle all the way down just to confirm if its rich or lean. I have had it to the dealer and they tell me its normal to run like crap at steady throttle. If I run it hard through the all gears it runs ok but I do run it on the street.

Is there something else that could be wrong that I should be checking?

Am i headed in the right direction with the EMM needle and smaller mj maj pj etc?

Thank you all. Matt

"Normal" to run like crap?

Don't take your bike to that dealer ever again. My '01 426 runs great at steady throttle.

I haven't experienced your problem so I cannot offer a solution. But what was the stock clip position? I would only try one clip position at time to see if there is no change, it gets worse, or there is improvement. If there is no change, then one more, opposite direction if it get's worse.

By allowing your bike to breathe easier (lid, pipe), you would think that it gets lean (more air flowing) and thus you should expect to richen the jetting.

Mine was doing exactly the same thing. I had to go richer on the jetting. Try raising the needle a bit.

I think the reason it runs better while accelerating is because of the accelerator pump is richening up the bike. When the squirt stops the bike is lean again.

I would never take my bike to that mechanic. What bike is SUPPOSED to run like crap? Who would buy such a bike?

Thanks for the replies. The dealer is definitely not doing the job. They told me they raised the needle 1 clip, was in stock position when I took it out. This is the 2nd time, on my R1 they told me the adjusted the fuel screws, later when I pulled the carbs the brass plugs were still in and 1 screw was fully closed. When I questioned them they said they replaced the brass plugs and that I probably turned the screw in while drilling the plug. Doubt it. Fortunately they haven't charged me for any of the service they didn't do.

Update on WR: I installed the EMM needle clip 4 and steady throttle miss was greatly improved. It still did it but now it only showed up from 1/8 to 1/4 throttle and not as bad. Idle and top end seemed to be the same. I moved the needle up 1 and down 1 and didn't get any more improvement however temp was getting cooler, will try it again. I then went from a 165MJ to 160MJ. It didn't change the midrange miss but I felt WOT acceleration had improved. I installed a 40 PJ from a 42, left the screw at 2.5 out and it felt snappy on the low end and I am now starting to like this bike. Mid range miss was about the same or slightly worse so I think I am still a bit lean just off idle to 1/4-1/3.

If raising the needle doesn't help, any recommendations on a richer needle? Or should I try the smaller air jets?

I will be riding this weekend about 3,000 ft higher in Lucerne Valley So Cal and I may leave it alone for now to see the altitude affect. I am stopping by Sudco today to pick up any jets/needle that you guys recommend.

Many thanks, Matt

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