Does this sound like a bad idea?

I have a stock'02 wr426. I wanted to do the yz timing,yz jetting, bk mod,acv mod and cut the grey wire. Is my beast going to run like a bat out of hell or like crap? Can all those mods be done without any problems? Is there anything else I have to take into consideration before or after doing them. Please help before I make a mistake :)

It’ll run more like a YZ, which is good :) (don’t leave it stock!). You know you’ve just scratched the surface? There’s plenty more mods to do, so get busy. :D Do a SEARCH for:

Air box lid or Carbon Fiber Airbox (CF air box= light weight but costly!)

Twin Air Filter (works for me)

YZ fender (allows the engine to breathe better)

Blue wire (HELP prevent fouling plugs) (you’ll need all the help you can get!)

YZ exhaust (cheap, lightweight, good performance)

Header (YAMAHA aftermarket works good for me)

YZ head gasket (thinner for more compression)

Coil on top of plug (Mike Deans good idea)

CR8EK (split fire NGK plug)

TPS (Throttle position sensor)

ACV (Air cut off valve)

756 (a great tire)

M12 (another great tire)

Subframe (forget TITANIUM, go aluminum)

Taff Timed Cams (better performance gain than YZ timed, but harder to do)

Mobil 1 red cap (helps to preserve your investment)

Good luck!


I checked the head gaskets for the european 2002 yz vs. wr and they are the same part numbers. Can you tell me what part numbers do you have for the gaskets?

Sabin, I believe that Rich in Orlando found the difference between the WR and YZ head gaskets. I did a search, but could not find the thread.

I have kept this mod on the back burner for the day I have to remove the head.

I too checked on the part numbers and it looks like the same head gasket for ’98 through ’01 WR’s and YZ’s.


I have accsess on yamaha EPC program, and I have checked there. For the 2002 there is no difference for sure!

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