YZ 426 ?'s

7 replies to this topic
  • axman2292

Posted June 10, 2007 - 06:43 PM


Hey there,

I have a couple of questions about my 2002 YZ 426.

#1- What is this thing I keep reading about called "The Gray Wire Mod"...does it apply to my bike and what does it do?

#2- I just got back from four days of riding in the Nevada desert. We were at about 4000 ft. and would take rides up to about 7200 ft. each day. My bike ran like a top...it always started on the first kick..never had one problem at all, I would ride it all day just ripping it on high speed trails and tons of climbing. I live at just about sea level.....and it never runs this good at home...ie. some times hard to start, bogs down on hills more, just doesnt feel as good as it did in Nevada. What do you guys think? jetting issue, fuel mixture...not to sure and all. Anyt help would be cool.

  • sheesfast

Posted June 10, 2007 - 07:12 PM


well I just bought my wr426 on saturday, but I hope I am still of help to you.
#1- This has info about the gray wire mod


#2- I have not experimented enough to figure stuff like that out, but I am guessing that it is a jetting issue.

Many other people will be able to go in depth with this.

  • shanedut

Posted June 10, 2007 - 07:34 PM


I did the grey wire mod dont know if its works or not. But the best thing you can do is the bk mod to the carb. This will help but you are probably jetted for higher altitude. Buy a zip ty fuel screw or similar too it really helps out. The bk mod helps limit the squirt duration which is way to long on 426's. Jetting is your issue but if the carb hasn't been cleaned in awhile it could need that done too. If you look at the jetting sticky you should be able to find a ball park figure of what your jetting should be. The other thing I suggest is the 450 cam mod so you can get rid of the starting drill.

  • axman2292

Posted June 10, 2007 - 07:40 PM


Cool thanks..shesfast....so where in Cali are you ...I am in the Bay Area....take care

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  • grayracer513

Posted June 10, 2007 - 09:42 PM


The Gray Wire Mod is a WR mod only. It's done to give a WR the same timing map as a YZF.

If your bike runs good at altitude, but not at sea level, your sea level jetting is too lean. A 160 at 5000' would translate to a 170 at sea level. A 42 pilot would go to a 45.

  • sheesfast

Posted June 11, 2007 - 06:35 AM


Cool thanks..shesfast....so where in Cali are you ...I am in the Bay Area....take care

I am in Orange county, SoCal. But I used to live Fairfield...

  • axman2292

Posted June 11, 2007 - 06:12 PM


thanks guys I will try to figure this baby out next time I ride......maybe I will have it checked at the shop...or maybe some one could tell me about how to rejet your bike..thanks again, axman

  • sheesfast

Posted June 11, 2007 - 06:27 PM


...or maybe some one could tell me about how to rejet your bike..

yah ill be waiting for this part also

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