HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
Ga426owner

Important: Grey Wire test on a WR426 test?

44 posts in this topic

Has anyone tried to disconnect the Grey CDI mapping wire under the gas tank at the black dbl connector? This seems to have helped eleviate the mid range bog that is noticable to me on my 426 & to the owners of 2001 WR250's.

My bike is out of town til Sunday, so I can not check to see if this works/applies to the 426. For more info check the WR250 forum, under "what is wrong with the wr's"

I need some feedback asap. Thanks

This only will apply to US-spec WR's, not sure about 1999-2000 WR400's.

The wire is solid grey, next to the striped wire.

Share this post


Link to post
Share on other sites

For what it is worth, I was told that the ignition retards in the mid range for noise emission tests. I am from Australia, and will chech if mine has a grey wire. Maybe that is what the grey wire does.

------------------

Tony Montana

Share this post


Link to post
Share on other sites

Did mine last night and took it on the road for a two mile ride. The studder at about 50mph at steady throttle was gone. Too short of a test to tell for sure. I am riding on Sat. will let you know how it goes.

Share this post


Link to post
Share on other sites

This shouldn't be too hard to verify. Put a tach and a timing light on your bike. Find the RPM range that you think the timing is being retarded and check the timing. Then disconnect the grey wire and recheck the timing at that RPM. You should find that the ignition timing (or advance as it is sometimes called) is different with the wire disconnected.

If you don't have a timing light you could have a buddy hold the throttle at the RPM you think is flat and just connect and disconnect the grey wire. You should be able to hear a difference in the engine as the timing changes. You might even be able to get to the RPM range you need to check with the idle adjuster, then you don't need anyone holding the throttle and you remove one variable from your test.

I've got a Canadian 2000 WR400 so I don't think I have this grey wire.

Since I'm hobbling around in a knee splint instead of riding for the next couple of weeks I will try to take a look at my bike and run this test if I have the wire.

Share this post


Link to post
Share on other sites

Isn't this the rev limiter wire? I'm not unplugging mine, floating valves are not worth it!

Jetting should be able to solve the mid range flatspot, IMHO. Maybe not, though, huh?

Share this post


Link to post
Share on other sites
Originally posted by mcarp:

Isn't this the rev limiter wire? I'm not unplugging mine, floating valves are not worth it!

Jetting should be able to solve the mid range flatspot, IMHO. Maybe not, though, huh?

Check out the thread on the 250f side, the rev limiter still functions with the wire disconnected. It seems pretty safe to try out because the Aussie bikes come stock with the wire disconnected - you can actually see this in the wr250f manual.

-Brett

Share this post


Link to post
Share on other sites
Originally posted by olson_jr:

This shouldn't be too hard to verify. Put a tach and a timing light on your bike. Find the RPM range that you think the timing is being retarded and check the timing. Then disconnect the grey wire and recheck the timing at that RPM. You should find that the ignition timing (or advance as it is sometimes called) is different with the wire disconnected.

If you don't have a timing light you could have a buddy hold the throttle at the RPM you think is flat and just connect and disconnect the grey wire. You should be able to hear a difference in the engine as the timing changes. You might even be able to get to the RPM range you need to check with the idle adjuster, then you don't need anyone holding the throttle and you remove one variable from your test.

I've got a Canadian 2000 WR400 so I don't think I have this grey wire.

Since I'm hobbling around in a knee splint instead of riding for the next couple of weeks I will try to take a look at my bike and run this test if I have the wire.

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

------------------

Tony Montana

Share this post


Link to post
Share on other sites

You can see the same thing in the WR426 manuel.

Mcarp, the problem is this: jetting does not fix this issue, there is a issue because the grey wire (only on US version)was installed to change the rev limiter in order to pass emission test for noice or dirty air. What it does is trick the CDI unit, effecting midrange, causing lack of full power in the powerband.

There is no reason to think that by unplugging this wire that damage will occur. Why? Because all other non-US WR's don't have the wire.

The WR250 post explains this in full detail.

Your choice to be cautious, my choice to make my WR run like it is intended to.

Share this post


Link to post
Share on other sites

GA-

Thanks for educating me on this. Seems like there's no real risk afterall. I was not aware the non-US bikes DO NOT have this feature, which I agree-tells me it's OK to unplug it.

Cool...I may just try it, although I do not seem to have any hesitation issues...

Share this post


Link to post
Share on other sites

The '00 WR400 wiring diagram in the manual shows this wire terminates at the connector from the CDI. It does not! The grey wire continues into the wiring harness at the connector to an unknown termination point.

Question is, What does the grey wire connect to?.............. (See below)

More to investigate.

[This message has been edited by James Dean (edited 06-08-2001).]

Share this post


Link to post
Share on other sites

James Dean, in the US 2001 WR426 manuel, you have the grey wire coming off the "B" line from both the 6connector(O:B:Sb:L:Y:B/L) to the CDI unit(left) & the sparkplug/ignition coil(Right). Both the Gy(grey) & the B(black)wire split off of "B" line, the grey going to the dual or (Gy:B/W)wires to the (B/W:Gy)connector which is the dual black connector back to the CDI unit. The "B" wire goes to the Engine stop button looping back to the black dual connector as "B/W" to the CDI unit.

On the non-US bikes the 6connector wiring is different with "Sb"(skyblue) wire taking the place of the L/W (Blue/white). I wonder why this is?

I know why the Gy(grey)for US -- emissions compared to the non-US (X:B/W)*Except for USA

James, I know this is confusing w/o a drawing, but is this the same on your 00WR400???

You should see the same benefit unconnecting the Gy from the dual connector as the rest of us if this is the same. Does anyone have a US 99WR400 manuel to check this???

Share this post


Link to post
Share on other sites

My engine's still in pieces, but I should have it running by next weekend. And I, too have been plagued with that annoying 50 mph stutter. Jetting changes have made it marginally better but haven't fixed it. I can't wait to get up and running again to see the difference with the gray wire disconnected.

Share this post


Link to post
Share on other sites

Noted above: The '00WR400 wiring diagram in the manual does not match the bike.

The gray wire off the CDI is visible going into the wiring harness. There are no other gray wires ANYWHERE coming out of the wiring harness. All the wiring harness plugs were disconnected and the gray wire only has connectivity to the BLACK ground wire at the coil. The CDI also has a black wire which is grounded at the engine via the 6 wire plug.

So... Why would the CDI need 2 wires of different colors both grounded, one to the frame and one to the engine?? :)

More to research.

Share this post


Link to post
Share on other sites

Mr. Georgia,

My '99 wiring appears to be identical to your 2001 bike.

------------------

'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.

Share this post


Link to post
Share on other sites

I just read through all the posts on that topic on the WR250 board so I went down to the garage and checked my bike. Mine is a '99 Canadian WR400 and the grey wire comes out of the CDI harness and goes to the black two wire connector and ends there. On the other side of the connector it is blocked off and there is no more grey wire. This must be a US model restriction only. I have briefly rode a couple US model WR's and they are soft through the midrange, my bike rips hard through the mid and keeps pulling hard all the way up to the rev limiter. If I had a US model I'd unplug this in a heartbeat and try it out.

Make sure you have the correct wire. On the harness coming out of the black CDI box there are three connectors. One of them is black with only two wires in it. One of the wires is black and the other is grey. The grey wire is the one.

------------------

'92 GSXR 7/11 (But I never ride it so you should buy it...)

'99 YZ400F 'cause thumpers rule and two strokes drool!

Share this post


Link to post
Share on other sites

Well, hope my CDI doesn't leave me stranded. A 60-80 mile ride is planned for tomorrow and it is disconnected. :)

Ga426owner, every indication is your description matches the wiring on my bike. I understand your posting after reviewing it and the wiring diagram.

The short test run feels like there may be more power. I need some wide open spaces to give it a good test.

James

[This message has been edited by James Dean (edited 06-08-2001).]

Share this post


Link to post
Share on other sites

ANy one have access to a dyno machine? it would be very interesting to see the diff this mod makes.

come to think of it, a dyno sheet on any non-US model that someone has would do it.

I wonder if the HP that Yamaha quotes is for the US or NON-US model?

I also wonder if the total max rev HP is effected since this was a mid range fix. Hmmm

Whether we get the answer from a dyno machine or not. I have done this mod and feel a big difference. I had not done any jetting previous to this though. So I would imagine that a bike that had made some improvement from jetting would not see as drastic a result as me.

mike

Share this post


Link to post
Share on other sites

I disconnected the gy wire on my 98 WR,but have not rode it yet.I reved it up and the rev limiter IS still there.I was hoping to get rid of it.My schematic shows the gy wire going to the connector, but nothing going out of it.

Jeff

Share this post


Link to post
Share on other sites

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
Sign in to follow this  
Followers 0