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steve lemley

Whats the grey wire do??? Should I cut it???

37 posts in this topic

I searched for grey wire treads and I cant find one that explains exactly what the wire is for and where to cut it :bonk: . I have a Baja Designs kit on my bike. Will the extra wiring from the kit alter the purpose of cutting it :applause: . In short, what does it do if I cut it and where do I cut it. Thanks again. :cry:

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The grey wire when disconnected, maps the ignition to the YZ configuratation. If you have installed the YZ throttle stop, you should do the grey wire mod. Only USA configuration bikes come with the grey wire attached--- its a smog thing. I can't tell you where the grey wire is located, because you didn't identify what model/year bike you have. The location of the harness that contains the grey wire looks slightly different between model years. They are all located under the tank and up near the steering head, however. You do not have to cut the wire, you can push the pin on the end of the wire out of the connector. Once the pin is removed, wrap it in electrical tape.

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Sorry the bikes a 99. The throttle stop pin mod has not been done yet but I plan on doing it this weekend. I can grind it down 8mm instead of replacing it with the yz one correct? Will I feel a difference if I make these two mods? Do you know where the grey wire is on the 99's? Thanks.

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Yes, you can cut/grind the stock throttle stop screw down. To what length, I don't know off hand, but you should be able to search and find it on TT pretty easy--or, maybe it's best to go to thumperfaq.htm under free mods and look there.

You should feel a difference once you cut down the throttle stop screw because you will be removnig the governor effect and letting the throttle fully open.

Do the grey wire. It is a ground wire, if I recall right, and having it disconnected/cut will map the throttle to YZ in the sense that the YZ does not have the longer throttle stop screw that stops the throttle from opening. Just for clarity, it is not the same thing as changing the ignition mapping or getting YZ timing by changing to a YZ cam.

I think I have said this all accurately. It is what I have heard on TT from those that really know.

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The grey wire when disconnected, maps the ignition to the YZ configuratation. If you have installed the YZ throttle stop, you should do the grey wire mod. Only USA configuration bikes come with the grey wire attached--- its a smog thing. I can't tell you where the grey wire is located, because you didn't identify what model/year bike you have. The location of the harness that contains the grey wire looks slightly different between model years. They are all located under the tank and up near the steering head, however. You do not have to cut the wire, you can push the pin on the end of the wire out of the connector. Once the pin is removed, wrap it in electrical tape.

Are you sure only USA bikes come with the grey wire attached?

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I disconnencted the grey wire but the bike tends to have black smoke out the pipe for the fitst couple of minutes any ideas on why. Becides that the biffernce is noticible!!!!! Thanks.

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Do the grey wire. It is a ground wire, if I recall right, and having it disconnected/cut will map the throttle to YZ in the sense that the YZ does not have the longer throttle stop screw that stops the throttle from opening. Just for clarity, it is not the same thing as changing the ignition mapping or getting YZ timing by changing to a YZ cam.
Actually, the gray wire IS an ignition mapping change. It is a trick used by the factory to help the WR pass EPA noise regulations and has nothing to do with emissions. That's why it is only on US model WRs. I got the info from a Yamaha engineer and wrote about this in the May '05 issue of Dirt Rider in an article about WR mods. The wire is connected to ground which forces the ignition module to use the WR mapping. Disconnecting it lets it use the YZ mapping. With it connected, the WR will not rev as high as the YZ. If you never cut/replace the throttle stop screw (designed in conjunction with the WR map to limit revs and therefore noise) you will see little if any improvement by disconnecting the wire. You must do both mods to see the full benefit. :applause:

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Mxyves,

To add to what CycleWriter has written, I searched the archives back to 2001. There are many threads about this subject. The consensus is that non-USA bikes have a grey wire that goes into the connector, but no wire comes out the other side of the connector --- the circuit is open.

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Go to thumperfaq. You will find a number of items on the grey wire, throttle stop and host of other free and cost mods that will help the WR.

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i helped my ridin buddy with his 03 wr 450 , we put a small toggle switch on his bars so he could go from the wr setting to the yz settingwith a flick of the switch . he says he uses the wr setting when he hits a tough hill climb and it seems to help out with the wheelspin ,he noticed its easier to lug it in those situations

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i helped my ridin buddy with his 03 wr 450 , we put a small toggle switch on his bars so he could go from the wr setting to the yz settingwith a flick of the switch . he says he uses the wr setting when he hits a tough hill climb and it seems to help out with the wheelspin ,he noticed its easier to lug it in those situations
In case anyone reads this and thinks it makes sense, I'm here to tell you it doesn't. The status of the gray wire is read at engine startup. Switching it while the engine is already running has absolutely ZERO effect on the ignition. Unless your friend is shutting off at the bottom of the hill, throwing the switch, and restarting, then any perceived difference is all in his head. :applause:

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After I disconnected the grey wire I really didn't feel a big difference from when it was still connected.

How about you guys? Would you rate the difference between cut and un-cut as un-noticable, minimal, or huge.

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maybe im wrong , but i rode it in a flat field with at least 1/2 throttle and then flipped the switch and it sure felt like it was making a difference . but ive been wrong b4

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Go to thumperfaq. You will find a number of items on the grey wire, throttle stop and host of other free and cost mods that will help the WR.

The link seems to only deal with the 250F. I am no mechanic, but I imagine doing the mods on the 450F is different. Or am I just a moron and can't find the 450 part of the page?

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As the last step in the installation instructions for the '05 AIS removal kit, Yamaha says this:

"Remove the gray wire from the CDI unit. This will change the ignition timing advance curve."

So, after installing the YZ throttle stop, rejetting, removing the airbox restrictor, and removing the factory exhaust restrictor Yamaha recommends disconnecting the gray wire. I'm thinking that the factory curve is designed to achieve green status with the restricted motor, while the disconnected curve is designed to achieve the performance that the engineers intended with the un-restricted motor. If you've done the mods, pull the wire. :applause:

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I'm thinking that the factory curve is designed to achieve green status with the restricted motor, while the disconnected curve is designed to achieve the performance that the engineers intended with the un-restricted motor. If you've done the mods, pull the wire. :applause:
As I've said in other threads on this, the gray wire/WR ignition mapping is designed for one simple purpose: to help the WR meet EPA noise regulations. It was designed to work in conjunction with the throttle stop screw to lower the accessible RPM range on the bike. It has negligible effect on emissions. Cutting the wire does not unleash some magical performance genie, it simply raises the rev limiter and provides a slightly more aggressive timing curve. To be fully effective one must also do the throttle screw mod.

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The link seems to only deal with the 250F. I am no mechanic, but I imagine doing the mods on the 450F is different. Or am I just a moron and can't find the 450 part of the page?

No your not a moron (well maybe, but not right now). The thumperfaq page is directed to the 250F, but all of the basic mods apply to both and there are some very good information and pictures. Anytime your not sure check the posts on the ThumperTalk Forum, somebody has already done anything you may want to do.

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i have a 2004 wr 450. where would i find the gray wire?

my local dealer told me that year didnt have one. i have my suspicions.

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Sounds like your dealer is a moron :thumbsup:. I don't know where it is as I have a 2003, but from what I read in TT, your bike has it.

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