I just bought a new 2001WR426F Canadian spec.(with sealed exhaust and no throttle stop)and I'm very dissapointed in the power.Whats the cheapest way to make it run with a YZ.eg pipe,timing,greywire,jetting. Bike starts and runs real nice but not alot more power than my old XR350R.thanks

Do the grey wire first and ride it. Then jetting (new needle, pilot air screw)I think your pipe is more free flowing than the US WR pipe already?? For me, the jetting, yz timing & yz pipe...whole other bike.

Do your search...all of these things have been rehashed a thousand times here. But, some of us will gladly assist you anyway. Search first though.

Not more power than an XR350???

Not possible.

You do not have to cut the grey/gray wire to by-pass the rev limiter! Instead, remove the gear shifter and take out the two phillips head screws holding in that little black housing with wires going into it. Behaind the seal housing will be a little plunger, the only thing sticking out is the head. Get a pair of needle nose pliers and pull out the plunger, it is only about 1/2 inch long. Then use a piece if wire or something to stick in the hole to remove the little spring that is found behind the plunger. Once these two things are removed, the automatic rev limiter will be disabled, however, the main rev limiter will still work fine. When I put the black housing back in, I went to Home Depot and picked up two 5mm x 16mm allen head screws to replace the phillips screws.

I have the same bike and have ridden a few others. They are fast right out of the box. Airbox lid on and all. If your's is no faster than an XR350 there is something very wrong. When running properly they are comparable to a healthy 250 MXer.

If your still want more power after you find the problem, switch to YZ cam timing.


Something is wrong here. I own both a WR426 (Australian model, therefore same as Canadian spec) and an XR350. There is no comparison between the two, the WR has WAY more top end (~40Rear wheel horsepower in the state you described, compared to ~24HP). I'd suggest ensuring that the WR is running correctly, then doing an accurate comparison. In drags with my friend on an XR350 the WR pulls away very rapidly above ~50kmh when the rear wheel has enough traction.

Or if your WR is running correctly you've had a mega XR350 !


He says Canadian spec model so there is no grey wire right?

Hmmm... maybe the cork thingy in the tailpipe is still in??? I unscrewed/trashed mine before I ever rode it, could that be it???? Is this flame bait??? My bike is bone stock less that cork, the airbox lid and the throttle stop were gone when I got it.

"Somethin ain't stirrin the Kool-Aid"

[ March 21, 2002: Message edited by: big_G ]

enduro dog is correct.. Then Go to YZ timing and roost! Perhaps my profile below will help you with the info you need.. Oh yea, BK mod is somtimes a good thing for 01's and earlier WR's


[ March 21, 2002: Message edited by: SoCalWR426 ]

Canadian wr has no grey wire. Pull the lid off the airbox. Pipe that bad boy( I use an FMF Powercore IV no spark arrestor) Change to YZ timing, check jetting. I also use the blue juice(105 octane). It's fast enough for me

just lose the stock exhaust and re jet...

Thats it..

I hope I did't piss anybody off bitching about my bike,I just had higher expectations.I can wheely them both in 3rd(WR taller gearing)but it really does lack the snap of a 250MX.Since I made that first post a have explored this site for about 6 hours and am overwelmed by the available info.I'm sure I'll get the desired improvements in time.In order?PowerCore 4,YZ timing,BK mod,Jetting?(ditched airbox lid,grey wire not an issue)Thanks for all the great info and the great site

I don't think anyone is actually pissed, just amazed that you either have one bad-ass XR, or something seriously wrong with your WR.

I would side with the latter. My bike is bone stock an does many a wheelie in any gear I'm brave enough to leave the throttle open in. Yes, that includes 5th. And my gearing, as stated, is stock.

You will not need any mods to achieve this level of performance in my mind. I can only imagine the 426 having equal if not more power than the 400's do, so your bike must have something wrong somewhere.

Did you pull out the muffler tip yet???

My Son's Calif. 2002 WR426 is as fast as My other Son's Calif. 2001 XR650R with all the Intake/exhaust mods/jetting on the XR and jetting/throttle limiter/restrictor plate on the WR, the only thing I can say the XR has on the WR is the bottom end torque, but it has more flywheel and 50% more displacement. In a drag race they are real close until the very top end where the XR will finally pull away, but if the YZ specs for the cams, and YZ jetting were used I think it might stay with it. I see more problems with jetting than anything else, so double check all the jetting/needle/clip position. Time spent here will be well worth it in the long run.

Bob J

The exhaust is welded solid except for short piece of pipe with less than a 1" hole in it.Is cutting it open,gutting it,and rewelding an option?The bike has only 30 miles on it so will it loosen up a little with more use and abuse?I've only ridden it at about 50 degrees,could the stock jetting just be too lean?Anyways,there's snow in tomorrows forcast so I'll have lots of time to search this site.

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