2003 WR450 sputters at low RPM

2003 WR450 with what I thought was a jetting problem. I did all the jetting recommendations and every combination of MJ/Pilot and needle. Grey wire cut, airboz open and Pro Circuit 496 muffler, TPS connected, throttle stop mod.

The problem is the bike stutters and hesitates just off throttle. Will sometimes idle ok and won't when warm. So from throttle position 0- 1/8+, runs like crap, which is not fun in some tight spots.

Took it in to check valves and get them adjusted and see if the dealer had any ideas. So far, after 1 week, no joy. They have not been able to find the problem. TPS checked fine.

Mid-range and WOT is just fine - no problems and nice acceleration. No popping or backfire on deceleration. Problem is just off idle.


You may need to try a richer pilot jet up to a 50 and make sure you adjust the fuel screw out around 2 turns to start with and then silver solder plug your leak jet. Some aftermarket pipes run lean right off idle.

I am wondering if there is something electrical-based causing the problem? CDI?

Searching the Forum, I found a couple of threads that describe the same problem. It appears that this is a common problem and the culprit is the TPS. I will focus on that.

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