grey wire

I am going to cut my grey wire tonight after I ride for about an hour. It is the grey wire, under the tank with a double black connector, is this correct??

You are correct sir!

I was able to bend the pin for the grey wire so that the connector could be closed again without the grey wire connection being made. That way I didn't have to clip the wire.

- Sean

My gray wire has been disconnected and must say that I'm quite pleased with the results.

On my 2000 WR the infamous gray wire is located on the bottom of the wire harness under the frame on the right hand side. Be careful - if the wires are dusty all of them look gray. The one you want to disconnect (don't snip) does have a two wire black connector.

What I did was cut the forward zip-tie that holds the harness tight, disconnect the black connector, push one end of the connector through to the left hand side of the bike (this gives you room to work), using a small flat head screwdriver I disconnected the gray wire from the connector (that sounds weird) and folded the wire over onto itself and taped it real good, squirt some silicone into the hole on the connector, and put it all back together. Hope that makes sense. I need more coffee…

I believe that this gray wire thing is the missing link from the WR (YZ timed) to the YZ. I've ridden YZs and always blamed the difference in the mid-range on gearing. Now the thing has the YZ feel I've been after. Smiles!

Now, what about those of us who are remaining WR timed? Is this just for the YZ timing?

Thanks for the info guys.

Mike -

I do not know yet. I will be switching back to the WR timing this week to test it out. Based on the magnitude of change it made on the WR250F - I have to believe that this will be benificial regardless of the cam timing.

- Sean

Does this Grey Wire issue also pertain to the 99 WR400 ? Is it located in the same place as the 00 model ?

My 2001 WR is still WR timed and completely stock except for the trimmed throttle stop. I have disconnected the gray wire and feel it makes a good bit of difference, in a good way.


I'm not sure about the location of the wire on other year models, but I would start looking in the same place as mentioned above. The reason I did not just clip the wire was so I could put it back in case I got it wrong or did not like the results.

I would imagine it benefits wr timed engines as well as yz timed units. Give it a try, heck, it's free and you could put it back if you want.

do others concur w/Carl? we WR-timed folks would like to know if it would also help us. many thx to all who have done the testing for the rest of us! bobwombat

Since the U.S. version is the ONLY model to have this disconcerting feature, whether WR or YZ timed, cut the bastard!

The 99 is on the right side of the frame backbone. Yes, I did cut mine!


'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, and I use MOBIL 1 Oil, with ZERO problems.

Yes,cut the wire!!!

I have a 2000 WR with stock timing.Cutting the wire made a very noticeable difference.Runs much better.No surging in the midrange.

Got home and the boys were ready to ride so I was rushed out the door before I could cut the damn thing. I was suposed to change my oil too. Soon as I get it cut and test it I will post.

Thanks to all for the help and the testing.

Thanks Kevin

Hi all, I'm somewhat new to the forum and the WR400. What is the grey wire? What does it do? And does my 98' WR400 have this grey wire? My WR is YZ timed, should I cut this thing?

Thanks, Chris

The grey wire mod came from advice from a Pro Racer from big blue who will remain nameless, His mechanic told me the correct way to fix this issue.(do not just start cutting wires - look at your manuel for the (Gy:B/W) wire going to the CDI unit page 6-1 in 2001 manuel) It only applies to WR426/250's that are US spec only. Look under your gas tank, for the double black connector(B/W:Gy) w/ 1-grey wire & 1-black wire. I suggest not cutting the wire, there is a easy way to disconnect from the dbl. connector if you are patient. You will notice more power in the midrange regardless of WR or YZ cam timing. Make sure you ground out the grey wire after disconnecting with elect. tape & silicone. The reason for the grey wire is to pass US emission test. This will apply to 1998-current WR's

Ok, what do you mean by "Make sure you ground out the grey wire after disconnecting with elect. tape & silicone."?

I'm still in the process of rebuilding the engine so my 99 is not running right now. I spliced in a toggle switch on the gray wire to test it when it's up and running again. But, does the wire need to be grounded? I thought everyone was just disconnecting the wire and taping it off or removing the pin so that the circuit wasn't completed.

[This message has been edited by Rich in Orlando (edited 06-22-2001).]

I put a toggle switch on the wire. Didn't notice any difference at Tower City ('00 WR400, YZ timed). Maybe I just wasn't ripping hard enough or was too focused on riding than noticing the performance increase.

Once I get to ride again, I'll test this again.


Information above states it may need to be grounded.


PS.. I crashed on the left side again last night just for you!

Uh... GA426 I think you misspoke. I think what you meant was not to ground it but to insulate it right? I mean how would you ground it w/ electrical tape & silicone? I disconnected mine alltogether and the difference is night and day.

To be clear: The grey wire out of the CDI is connected to NOTHING!

- Sean

Grounded or insulated? I put heat shrink tubing and dielectric lube on the wiring that I ran to the switch. I did NOT ground the wire. What's the real story folks?

Mike, funny I ALWAYS crash on the left. Maybe that's why my radiator is bent on the left and pristine on the right? How are those beer stickers holding up? :)

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