WR426F 5th gear judder

I have a 2002 WR426F which feels like it has a fueling problem but only in 5th gear under load. It feels like I am running out of fuel but it is too uniform, it picks up then backs off around 2 times a second - constant. I have just had it set up with brand new factory jets at factory settings by a garage, they then road tested it and it was still there. They then tried two different clutches, but it is still there. It seems odd that it is only in 5th as when the WR's have a gearbox problem (I don't think this has) it is normally 3rd that plays up. Could it be something as simple as a sparkplug or HT lead?

Any help would be greatfully recieved - I'll buy you a virtual beer!


My bike has always ran like that at a constant throttle in 5th gear going about 50 mph. Do a search in this forum and you'll see all kinds of discussions about this subject. It's normal and you'll just have to get used to it.

It's not the usual light judder that normally occurs, it is quite violent, like opening and closing the throttle. My mates bike is exactly the same and is nowhere near as violent.



Try unplugging the Throttle Position Sensor, and see if it still 'surges' under the same conditions. My '02 426 used to surge, although not as violently as you're describing.....Do a search on 'TPS' in this forum, plenty of reading there.....

Sounds like an ignition problem. Not to sure the differences between 426 and 450 but would check the plug, plugwire, neutral safety and tps if equipped for starters. Might also want to check kill switch, it might be vibrating and intermittently shutting off the ignition. Would think it's something simple and not major if runs fine under all other conditions.

I'd bet that the dogs in third gear are rounded out (3rd gear drives 5th)

Been there, done that.


I have to agree Hamish, must be gearing so I'm gonna split the case on Tuesday and see. Either dogs or tooth missing - bet ya!@


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