Important: Grey Wire test on a WR426 test?

The CDI worked perfectly on an 82 mile ride today with the grey wire disconnected. Never missed a beat and ran great.

Mike, you were right. Removing the grey wire was a small improvement in comparison to jetting changes. Midrange power seems a little stronger.


Originally posted by tonymontana:

Hey Olson

Check your wiring diagram, my Australin model 01 wr426 has the grey wire and as far as I know the Canadian and Australian models are the same. I will disconnect mine for a ride on monday ( public holiday in the colonies for her Majesty's birthday ).

I'll keep you posted.

Damn the torpedoes full steam ahead

Very sorry Olson, I goofed. we don't have the grey wire. the wire is capped at the conector. But if I had the wire, I would disconnect it. My bike runs like a clock and have always wondered why the American models had trouble with jetting, fouling plugs and being hard to start. Sounds like the grey wire might be responsible.


Tony Montana

Cool now we can splice into the CDI and put a switch on the handlebars and have two settings like the Husaberg and KTM guys. Thrill me with rapture! If it gives me more boost, snip and it stays that way. This is the factories way of gaining an extra couple of ponies on the rest of us without works parts? Who knows. Somebody else find me 5 more horsepower for free. What else can I unplug?

Just disconnected the gray wire on my '98 WR400. Let my brother take it for a ride, told him something was different, but not what. He came back and said it had more midrange and a smoother transition to the top end. Wire is now pemanantly disconnected. Interestingly, my manual's wiring diagram shows the gray wire going from the CDI to the two wire connector and stopping there as on the non USA bikes. On the bike, the wire did continue on from the connector. I've been trying to smooth out the midrange/top end transition with jetting, and was marginally sucessful. Gray wire snipped, problem gone.

How about a picture of the gray wire?

I am gonna give it a try, thanks to all for the input. 1 question, did you notice if the rev limmiter still worked??

[This message has been edited by mike68 (edited 06-11-2001).]

Nothing like the band wagon...cut mine this morning!


'99 WZ/YR (you choose!) with ALL YZ mods, de-octopused, DSP Doug Henry airbox w/ velocity stack, FMF PowerBomb header, Stroker SX-1 silencer, SS front brake line, forked over by Pro-Action (and then fixed by me), OEM YZ tank, IMS YZ seat, carb mods by Jim Dean, Andy in OZ, & Sir "Taffy" from Jolly Old England, AMA, NESC, GRAY WIRE CUT and I use MOBIL 1 Oil, with ZERO problems.

[This message has been edited by NH Kevin (edited 06-11-2001).]

I haven't noticed anyone mentioning if this is the same on the 99'YZ400. I don't see why it would be any different but who knows. I just saw this post this morning and I won't have a chance to inspect the bike till sometime mid week.



When in doubt, GAS IT!

What are you, YELLOW?

If it's dirty, I do it and think it!!

I have a 99 WR 400 and looked at the diag, grey wire shows dead end, its not, it dose go down to the coil, looks like it senses RMP from the coil for the map overide threshold ranges . So I clipped it and started the bike. It still ran and kill swith works. I took the bike out riding hard on Sunday. This is my first hard ride with it where I was able to wring it out so I can not give a compare report. I am having idle and jetting issues as well but its not from the gray wire cause I hooked it back up to see. I will take the jetting back to stock and start from there, but the clipping of the gray wire has not hurt the CDI after 30 miles in the hot coal dust, and the 99 WR 400 US gray wire DOSE continue to the coil despite disapearing on the diag. There is no note in the manual about a US and or non US model.

Yes, the rev limiter still functions fine.

The limiter still works on the non USA bikes, so why wouldn't it? I wouldn't think any of the YZF's would have this wire, only the WRF's.

Has anyone tried putting a switch on the wire to see how much of a difference it really makes?

After reading the many reply's on the 250 forum, I noticed that some of the 400/426 owners stated they could tell some difference with the gray wire diconnected, but not as much as the 250 owners. My wr426 is completely stock except for a trimmed throttle stop. I have wr timing, airbox lid, and stock insert installed. I have over 500 miles on it this way. Today I disconnected the gray wire and spent some time riding around a one mile course I have on my 40 acres, and I find quite a bit of difference. Maybe not as much as the 250 guys have found, but it definitly livens things up. I have several over 90 degree turns that used to require a slip of the clutch from down low in second, but not now, just throttle. Front wheel comes up easier, also.

I did, about a week ago, put an experimental insert in and ride it few times around my course before putting it back to stock. I was alittle disappointed, as the added power was great, but I didn't have time to mess with the jetting alot and was going riding the next day. Although the gray wire fix does not give the same increase as opening the exhaust, I think it is a good middle ground for those of use that like the quietness of stock.

If this little grey wire affects the timing, wouldn't that mean one would have to rejet after cutting it. Im going to look for the wire on my 00 wr this week and give it a try. has anybody had enough time to jet differently with the wire cut? If spark is more advanced do I need to go richer? A picture of this infamous wire would be great.


y2k wr, airbox lid and baffle removed, 180 main, 45 pilot, 426yz er needle,

wr timing


Send me an e-mail. we need to finalize plans for wednesday.


I snipped the grey wire last night and it did smooth out the surging in the midrange. This only occured at a steady half throttle so it was no big deal. If I was running WFO thru the gears it was not noticable(the surging). I experienced no obvious power gains thru the rpm range but the smoothness is definate. I have a '00 WR, stock w/the freebie mods, needle at #4, 0-2000 ft.


Going to ride with us this weekend? Use the email in my profile, give me your phone number and I'll call.



97 KDX220, 86 TTR225, 99 WR400f, WR timing, MX-Tech suspension, throttle stop trimmed, air box lid removed, White Bros head pipe, silencer and air filter. De-octopussed. Works frame guards and Thumper Rad Guards, Scotts steering damper. Odometer and headlight removed. Cycra Pro-Bend hand and mud guards. YZ stock tank, IMS seat and number plate. Renthal Jimmy Button "highs" and Renthal Soft half waffle grips. AMA, SETRA, Happy Ramblers MXC, Rausch Creek MXC, Tower City Trail Riders.


if your going to test, test properly. i'm suprised so many people have gone for a quick thrash & said it's a big improvement.

give up at least a whole morning & do justice to your back-to-back testing.


for &%$#@!s sake we (you) look silly enough as it is given that it's only taken four years for this mod to be mentioned! i don't think you ought to crow about this one in the bar lads-do you!!!

so let's take it nice & slow & get it right. it's great to hear of yet another all win/no lose , mod if it works.



Taffy, now now....this mod did take some effort to find out & a lot of testing prior to this post. Get this: I believe the 2002 Yamaha 4strokes that all announced new ignitions today on the Yamaha - USA web site, probably they have the infamous "Grey Wire"

solution fixed, along with so many more drastic changes....ha .....ha ....ha!!!!!!!

And they did not think we could find out????

After changing to the YZ timing the WR runs rich in the middle anyway. I had to go a leaner needle (DVP?) and set the clip to the third groove just to get thru the midrange without missing. When I disconnected "the wire" (actually, pushed the terminal out of one of the connectors) the midrange improved. I have not messed with the jetting since and have been happy with the result. The change is most evident when accelerating from idle to the rev limter in one gear. Instead of feeling a huge top surge because of the soft middle, the power is nearly linear. I am running ('98 WR400) a 48 pilot, 178 main, DVP-3 needle, Pilot screw at 2-1/4, K&N air filter, airbox lid removed, Supertrapp IDS quiet core with six disks (not so patiently awaiting a FMF q-series) in Michigan (approx 800 feet). I think it runs pretty darn good, and is not as prone to stall as a stocker.

Good tip Tony Miller. Wanted to try disconnecting the grey wire but didn't want to cut it. Pushed the pin out of the way, now I can give it a try this week end.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now