2002 WR426 - Cam timing ,Grey wire, Exhaust

Just got a 2002 WR. I already pulled exhaust plug and removed thottle stop. So far I love the bike. I going to cut the grey wire next.

My question is there a after market exhaust that has the same or better performance that is not so loud.

The YZ cam timing I,m going try it after I,m used to the bike. I have heard differance storys on what it will do to performance. I like to hear from someone who try it both ways.

One last thing any one run in East coost - CT area . Any jetting suggestion. Right now it seem to run great stock. No problems

Thanks in advance

If you haven't cut the grey wire yet, don't. If you will unplug the two wire connector it is in and get a very small screwdriver you can push the wire backwards out of the connector, fold it back and tape it to the harness. No burnt bridges.

DO NOT mess with the wiring at all! Remove your gear shifter, take out the two phillips screws and remove the black housing that has wires running into it. Get a pair of needle nose pliers and remove the little 1/2 inch plunger, then get a piece of wire and remove the little spring from behind the plunger. Cap it back up and you have by-passed the rev limiter with out messing with anything electrical. Plus it is easy to put back stock if ever needed! NOTE: the two phillips screws are lock-tited in there good, and you will more than likely mess up the heads. I went to home depot and bought two allen head bolts to replace them, they were 5mm X 16mm if I remember correctly. Also, before you run to home depot, push the black housing back into the engine because you will lose oil !!!!!

do the timing it helps sooooooo much i just got my 02 wr a month ago it's great and for the pipe fmf q pipe works the best if you want it quite and do un plug the grey wire

By removing the plunger and spring you are by-passing the rev limiter! This is the same thing that cutting the grey wire does, except it eliminates the hack job!

i recommend installing a purple wire or pink wire in place of the grey wire because electrons flow better through fruity colored wires.then take a muffler off of a saab spg and install it in series with the wr muffler, that might quiet it down one or 2 decibals.then use reverse osmosis to convince the plunger that its not really there.then with the cam timing remove sprockets and remount them upside down and backwards(timing marks may be irrelivent with this mod).this mod works best with handlebar streamers. good luck.

On a WR250F, the grey wire affects the timing map but not the rev limiter (still around 13.5K), i.e., all it does is change the ignition timing (back to the YZ ignition timing map).

The light blue wire apparently connects to the neutral detection circuit. Apparently that changes both the ignition timing in neutral and engages a more restrictive rev limiter. Local hop shop owner swears WR250F has a 7.5K rev limiter because he tested it. What he doesn't know is if the bike were in gear, it would have rev'ed to 13.5K.

I've read (on this forum) three possible explanations for why the hell Yamaha would have this here (1) noise measurements in neutral, (2) protection from reving on stand, and (3) protection from missing a gear, hitting neutral and overreving. I think all of these are weak. Could be overheating protection while on stand (retarded spark, less heat while no air through radiator).

If you pull the light blue wire, you don't lose the normal rev limiter, you lose the more restrictive rev limiter (and timing change) that only occur in neutral.

Does this change tuning on brake dyno, since that testing is all in neutral?


arent all dyno tests done in neutral.i think they connect the dyno to the the head bolts to measure torque.then they check airflow from the intake on the exhaust system.also walmart sells the best handlebar streamers ive ever seen.also wearing a pink football helmet helps.

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