What are these wires?

I removed a grey loking wire also, but it may have been brown that looked grayish. The thumperfaq that you attached only mentions a 2 wire connector. I'm pretty certain that I have the US model. I have the 3 or C in the VIN.

Just checked my owners manual that came with my 02WR426 and there is only one grey wire shown on the whole schematic. It is in a 2 pin connector, and my drawing matches the one posted earlier in this post exactly. WR_Dave has posted the link to the ThumperFaq page for this mod earlier and it too is correct. Keep in mind that it shows two different year models, there is one for the 2 wire connector and one for the 6 wire connector. The bottom line here is that you want to find the one and only grey wire that comes out of the CDI and disconnect that wire. Hope this helps,


I'm good, the wires were located. Mine does have the blk & white wire instead of all black. Probably the difference between the 01 & 02. Thanks for the follow up.

No, that's the wrong set of wires. Look at the schematic carefully...SC

Well I finally had time to look at it again and only found one 2 pin connector. I looked at a downloaded PDF of EC612000 and didn't see a 2nd two pin connector in the wiring diagram. I just saw the one two pin that I posted up. The diagram I have shown has a BW and a Gy in the 2 pin. This is the only Gy wire I can find. So it matches the diagram I have and will be removing it. Update it later today.

Sounds good. I think we've all come to the conclusion that there's only ONE grey wire on the bike, so that kind of narrows things down. Like I said before though, make sure you only do the Grey one and leave the other plugged...SC

Just got back from a ride, a very nice 65 and sunny day here in NC. Seems to work fine, I think there is a little power difference. I think the front wheel came up a little easier. Well, probably not.

Now I just have to figure out this TPS thing and how to adjust it without a multi-meter. And if how the street adjustment affects it off road.

I don't think you'll notice a huge difference. The new ignition curve really only accounts for the gain in open throttle once the throttle stop has been cut. I would recommend not touching the TPS at all. Without a meter you'll never get it right. If anything, try riding with it unplugged at the connector attached to the frame. If you have not done it, do the exhaust cam mod and run a richer needle and main(depending on you altitude ect...) .

If whatever reason I need to tear it apart other than a valve adjustment I will be leaving the motor stock. Maybe some bolt ons, but I am plenty happy with the factory power. Even if I have to rebuild it I will be buying stock replacements.

The cam upgrade mentioned above is not only a performance gain, but it gets rid of the whole starting procedure on the 02 and earlier WR's. You can still use OEM parts to do this upgrade, and if you don't want the YZ cam you can even go with an 03 WR cam if you like. This was second best mod I did on my 02, the first was the Guts Racing seat foam! Anyway, Just a little more information on the cam swap in case you were not aware. Hope this helps.


I haven't researched much about internal engine upgrades, so what do you mean it gets rid of the starting procedure? Do you not have to use the decomp lever or what.

Exactly, the upgrade to an 03 Yamaha cam or the Hotcams cam eliminate the manual decompression. Either Yamaha cam can be installed without any problems, the timing is a little unorthodox but fairly easy to set and the setting has been proven here on TT. The Hotcam just drops right in and both are a good power boost as well. The biggest advantage for me was the auto-decompression. Starting is much easier now. If you want to persue this further I would be glad to help with the installation, if you want to research it then just search here on TT. There is more information on here than you could read in a week. Hope this helps,


It is well worth the upgrade. Before you do it, I would recommend just retarding the exhaust cam that you have so you can see the difference in performance before you spend the money on a 03 Wr cam and then to later realize that you should have gone with the YZ one. The power delivery of the yz setup is still very mellow since the wr has a heavier flywheel weight. It should only take you about an hour to turn the cam back. It will also give you a good opportunity to check your vavles. Just be carefull not to drop the clip under the cam cap. If you are near sea level there you should definitely rejet though.

Josh, thanks for the offer of help.

I will probably do the upgrade when I need to do a adjustment, that is if I have the money at the time.

No problem, let us know if you need help when you decide to get this done. Glad to help,


Wow that cam mod sounds like its worth it if I wouldn't have to use the decomp lever any longer. I will search ebay to see what I can find. I have the 02 wr 426, exactly which cams can I use? Thanks gang

You can use any of the auto decomp cams from the 03 and newer YZ. However, the easiest install will be of the Hotcam for the 02 WR/YZ. Both provide much improvement over stock, however the Hotcam is a bit easier to time. You shouldn't have much trouble finding an 03 YZ cam, and there is a ton of information on TT for doing this swap. If you need help, just let us know and we can walk you through it. Pretty simple as long as you have a good 3/8 or 1/4 drive torque wrench. Hope this helps.


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