On my 02 wr426 it like to kinda jerk when i hold the throttle about 1/2 way in higher gears. It is kinda annoying as it will get me rocking back and forth on the bike when im doin like 50mph. It is jetted to my knowledge, has an autoclutch, and has YZ cams and a DR.D exhaust. Also, if i put more baffles in my muffler will it kill perfomance and will i have to rejet it? This thing is annoying loud, even to me with my helmet on.

Not sure if the 02 has a TPS on the carb, but if it does, try to disconnect it. If it helps, than definitely not a jetting problem. If it works, search the forums (WR and Jetting) for "TPS", "ACV", "Air Cut Valvle", "Stutter", "hesitation" and you should find plenty of info. Since I disconnected the TPS, I got rid of the stutter, hesitation at constant throttle.

My 2004 WR450 has a throttle position sensor, I disconnected it to get rid of the stuttttter and it worked BUT I have since had my bike jetting set up at the Dyno Centre and they re-connected the TPS and jetted the bike correctly. RESULT FANTASTIC, it is like a different bike and NO stutter with the TPS re-connected. I know that TT members recommend disconnecting the TPS but from my experience I now know the stutter was from wrong jetting and on my bike STOCK was way too lean!! My next new bike I will be going straight to the Dyno to have the jetting set up properly - no more guess work!!

Hope you manage to get it sorted out (the cure for my bike was increasing the main jet 10 points from standard and the air screw from 1.25 standard to 2.5 turns out, but I am not suggesting this will cure yours, I suggest book into your nearest reputable Dyno Tuning shop and have them set it up, it cost me £140 UK aprox $250 US and it was worth every penny!! I liked my bike before but now it's like a different bike - FANTASTIC!!

Cheers Alex Robinson UK

Oh yeah, I forgot to mention, get the muffler sorted out to be as quiet as possible, even if you loose some horses, noisy bikes will be the downfall of Off Road Riding in England, and probably everywhere else in the world. I am pleased the manufacturers have started to make the 4 strokes quiet, but some of the older bikes are still way too noisy.

Cheers Alex Robinson UK England

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