YZ 450 Cams in WR 426's?

14 replies to this topic
  • RSA210

Posted March 07, 2003 - 09:13 PM


Just looking for a little feedback from those who have taken the leap and installed the YZ 450 auto-decompessing exhaust cam in their WR 426.How many hours/miles have you logged on since the mod?I'm sort of toying with the idea myself after reading about it on the YZ side.Anybody have any new info about the aftermarket cam manufacturers coming up to the pump on this yet?I think it may have been HotCams??Any Thoughts?

  • yamaha.dude

Posted March 08, 2003 - 12:47 AM


I have over 950km's (600 miles) on mine... no problems... I checked the valve clearances the other day, they are the sames as when I put the cam in... :D

The aftermarket cam places like HotCams are reported to be working on something, but they have also said they will be a few months away yet... :)

It is a great mod, just be aware if you want to maintain the WR timing, you will need the WR450 cam... for YZ timing, the YZ450 cam...



  • blue_beast_wins

Posted March 08, 2003 - 02:32 AM


About 850 ks here, no worries. :) :D :D :D

  • woodsrider426

Posted March 08, 2003 - 04:46 AM


I just picked up my WR 450 E cam for my 02 WR 426 yesterday, I think I paid around 165 with tax. It seems like alot of riders are doing the swap with good reliability. I am also going to keep the manual decompression.

  • RSA210

Posted March 08, 2003 - 05:14 AM


Wow...Over 600 miles & no problems.The way I understand it the YZ 426 guys are saying the YZ 450 cam makes the power more linear,which would kinda be somewhere between the feel of standard WR timing vs.YZ timing w/ the 426 cam.Kicks like a two stroke,you gotta love that :)
I guess much thanks is due to all the brave souls who took the leap so we all could learn more.Thanks to you.
And they said it could'nt be done.

  • x2smoker

Posted March 08, 2003 - 09:17 AM


Has anyone yet posted instructions for this mod? It sure looks like the way to go! I am just looking for any difficultys, special considerations, ect.


  • blue_beast_wins

Posted March 08, 2003 - 11:26 AM


Here is the instruction sheet,


The power is much more progressive with more power all round.

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  • yamaha.dude

Posted March 08, 2003 - 11:31 AM


The instructions and discussion have been going on since about November last year... pop over to the YZ4XX board and look at the post at the top with over 10K views... the instruction sheet is www.just-ride-it.com/450cam.pdf

The power is more linear, deceptively so... like a really fast WR... combine it with the JamesNOW! mod and you have a potent combination that will launch itself out of corners and over rock and ruts... you can loft the front wheel at will, any gear... and the bike just keeps hauling until you shut it off... if you can use all the power of this bike, then I want your autograph... because you are one hell of a rider... :D

There is no mid range hit as such... they seem to have bought the bottom end up to match the mid range... it is just fast everywhere... :) :D


  • AZWR426

Posted March 08, 2003 - 04:22 PM


Regarding "and they said it couldn't be done" THEY ARE STILL SAYING IT CAN'T BE DONE!!!!!!!!!!!!!!!!!!!!!!!!
I went to my dealer and he said even last week Yamaha had the dealers in a meeting and said "you will see it all over the internet, but IT CAN'T BE DONE!!!!!!!!!!!!!!!
I took in the dyno runs and instructions from just ride it and started to make a few believers. Mark

  • yamaha.dude

Posted March 08, 2003 - 04:55 PM


Hey, they can come and ride my bike anytime... LOL...

It would be good to see them scratching their heads when they realise... You think they would just do it for themselves and work it out... I doubt a few privateers need to be the ones showing the way for the R & D labs at Yamaha Corp.

Open invitation to any Yamaha Tech or Management... come ride my bike and I will pull it down afterwards and you can inspect it...


  • RSA210

Posted March 08, 2003 - 06:11 PM


Oh Yeah,the hit in the middle AND down low... sweet
I believe the post on the YZ side is an all time record,over 10,000 hits,unreal :D
It just sounds like Yamaha does'nt want to assume any liabilty for recommending this mod.to the general public,hey to each his own.You just can't deny the attention this is getting.Great job with the .pdf file,downloaded last week. :) :D :D

  • blue_beast_wins

Posted March 08, 2003 - 11:51 PM



whats with these idiots?? cant do this, cant do that, cant they think outside the square??

  • AZWR426

Posted March 09, 2003 - 01:22 AM


I think they want to sell new bikes bad enough in an economic downturn (expensive toys don't sell) they will say anything to keep the uninformed in the closet. True they have liaibility issues, but I think the biggest issue is NEW BIKE SALES.

  • x2smoker

Posted March 09, 2003 - 05:32 AM



Thanks a bunch for the link to the instructions. Another extremely well put together presentation! I didn't see a name attached to it, but "Hats Off" to whom ever authored it!

I do remember when this topic first started on TT. Then it kinda dissapeared from the front pages till now, now that it has been proven and time tested, at least regarding the 426. The 250 mod, as I recall, was pretty much a no brainer.

I assume that the dyno comparison was done using a YZ timed bike to start with. There I go, thinking out loud again! Of course it was, otherwise it wouldn't be a fair comparison.

Thanks again,


  • blue_beast_wins

Posted March 09, 2003 - 10:51 AM


The instruction sheet was put together by YamahaDude and Yamaben.


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