wr gray wire

I know of people cutting the gray wire on wr250's. will the same work for a wr400. also how many people have taken out the throttle stop or madified it? what advantages have you noticed.

2000 wr400, dunlops and many replacment plastics.

A buddy of mine bought a '98 WR400 this past week. He got it and thought it was a rocket! I rode it, and told him that he has much work to do to make his '98 WR400 as fast as mine. He thought "sure, whatever..."

So, we are out in the sand desert area riding on Saturday, and we are riding up this huge sand pile. His bike was making it about 1/3rd the way up, mine was cresting the top. After seeing that happen about 4 times, my buddy says "Here man, let's see you do it on my bike." So, I hopped on and gave it a go. Made it about 1/3rd the way up, and that was it. So, he hopped on my bike, gave it a go, and he saw the veiw from the top of that sand pile. He comes down and says "We are riding different bikes. It is like Night and Day!". I smugly smiled.

Anyway, so we then looked at his grey wire. I told him that is the difference between Emission's compatable WR ignition mapping and Flat-Out Rippin' YZ ignition mapping, so we pulled the connector, pulled out the grey wire, and reconnected the connector.

That gave him a new bike. He was hootin' and hollerin' for the rest of the day. I don't know how big of an impact this will do on a '00, but on a '98 it is significant.

Cutting down your throttle stop will give you access to much more throttle. Just make sure that you do not cut it down too short. That will create problems with your carb slide plate. Only cut down far enough that the slide can go up as wide as the opening through the carb. Any more, and the carb will recess up higher into the carb, and that will create turbulence that can crack the slide.

Good luck. Both mods are worth the effort, some are worth more than others. Don't cut the grey wire, pull it out the back of the connector. Won't cost you a dime and is very reversable.

Good luck!


Didn't you need to fiddle with your jetting to get it to run with the grey wire cut? I was curious to know what it actually did so I wired in a toggle switch so I could toggle back and forth between WR and YZ mapping in order to evaluate the mod (I realize that the CDI queues this on initial start-up only so toggling during a ride does nothing, it must be toggled and then restarted). Anyway, Running in grey-wire cut mode my bike pops and sputters like crazy like it needs some serious jetting work done. Jetting in WR-mode is just fine. I really like the idea of the mod but need to know if people are rejetting even though you don't hear much about this on TT.



I did no jetting changes (to mine when I did it, or to my buddy Jim's bike this weekend) to accomodate changing from the WR ignition mapping to the YZ mapping. What you are describing is exactly why I moved over to the YZ route.

At constant throttle (in WR mode), I would have an intermittant "miss" that drove me nuts! I thought there was something in my carb, dirty air-cleaner, something that would make it miss. Then, I pulled the grey wire, and it all went away! And, the bike seemed to run better and felt "snappier". I also saw those same results in Jim's bike this Saturday.

No jetting changes here for the Grey Wire mod.

Hope that helps you, but I doubt it does. Sorry.


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