New to forum and need help with WR426

I am new to the WR forum and need help. I just picked up a stock 2002 WR426 with no mods and am having throttle problems. The bike is very twitchy at low throttle. It lurches when you let up on the throttle and then re-apply it. The best way to describe it is it is almost like the chain is way too loose. I have a 2003 WR450 that rides nothing like this (it has all the mods though). The 2003 has a smooth throttle transition. Any ideas what it may be? I did check the throttle cables and they are OK and move freely with very little freeplay.

Thanks~! :thumbsup:

sounds like a clog somewhere in the fuel delivery. Perhaps old gas deposits? Try using some carb cleaner injected into the fuel line and letting it drain through the outlet accessed by the allen screw on the side of the carb. Also you might run some fuel cleaner in the next tank of gas, but of course that is more a fine tune for later.

Tried cleaner, didn't work. Removed and cleaned carb (Not much dirt in the bowl), still no luck!

Did you check the accelerator pump squirt? this will contribute to lowspeed/ small throttle opening hesitation. if the accelerator pump squirt is a problem then search for the BK Mod. make sure the rest of the carburetor is clean and working properly.

When you had the carb off did you record what jets you are running? I have the same bike and ride in CA. Here is my current set-up.

Model (400 - 426 - 450): 02 WR426

Timing (WR-YZ): YZ with 03 exhaust cam

Main jet: 170

Pilot Jet: 42

Fuel screw (turns out): 1 1/2

Needle model/Clip position: JD blue needle postion #3

Airbox lid (on or off): Lid Off

Pipe: White brothers e-series w/six discs and quiet core insert

Altitude where you ride: So Cal 0-4000 ft

Temperature where you ride: 75-110

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