The Gray Wire


I've done all the usual mods to my 2003 WR450F but not the gray wire. The May 2003, page 48 Dirt Bike Mag states "Some riders cut the gray wire leading to the throttle sensor on the carb, as well- that advances the spark at low RPM" That sounds like a good thing because advancing the spark(timing) makes more power= more low-end. Why is this wire there? An enduro version of a motocross bike needs more low-end. There has to be another reason for this wire. Any insights?

Tim :)

Only on US destination WR bikes. It is not on the Canadian, European or Australian bikes. Has to do with our wonderful EPA laws which somhow treat the WR like a street bike due to the headlight. Go figure one end of our government does not understand what the other end is doing. Now pull the gray wire out of the connector under your tank. :)


I answered my own question. I have a Canadian bike and it does have a gray wire. I pulled it and now I have even more power! This thing now wheelies through the first three gears with the front end anywhere I want to put it. Before rejetting and the wire removal, I had to give the bars a slight tug to get the front end up. Now it's just a flick of my right wrist!

Tim :)

2003 Canadian WR450FR, Maier extreme pro hand guards, Flatland racing radiator guards, YZ stock needle @4th position, 155 main, 42pilot, 1 3/4 turns air, Supertrapp w/ 6 discs, Gray nah, throttle stop and air flow restrictor does not exist on Canadian bikes. 9,100 feet above sea level.


I met a guy in a parking lot down at Hatfield McCoy from Michagan with the T.T. name of Mcgrath or Mcgraph but he new his stuff on WR mods do a search under the Grey wire and look for his post. He put an osilla scope or something in or on his bike and ran some tests and then plotted the out. He said that he found that on his bike which was a 2002 250 the grey wire made a big difference but only if the bikes muffler was uncorked or the spark arrester openned up. But, check his post out the guy is an engineer for Chrysler and does emmission test and knows the bike well.

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