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Birdie426

Cams, Cams and More Cams

5 posts in this topic

OK, guys, a little help here. I've searched the forum for the answer...but can't really find it specific enough to satisfy myself before I drop some coin.

I want to install an autodecompressor exhaust cam in my 01 WR426. After 6 1/2 years of mechanical engineering school (BS and MS in Mechanical Engineering from Cal Poly), I just can't convince myself, maybe because I don't have enough of the right info, that installing an 03 WR camshaft in my 02 will last forever. I've heard that not only is the pitch circle of the cam gear different (which, by itself isn't necessarily and issue), but that the tooth profile is as well (which could be). My anal retentive Engineering education just won't let me do the swap without the answer...are the tooth profiles different? Yes, I know that folks have had these installed for thousands of miles, but I'd always be wondering, and piece of mind is worth the extra coin.

If the tooth profiles are different, I'm gonna be a chicken, and find another solution. Here's the next question...whilethe Hotcams website doesn't specifically address the cam timing issue, I assume their cam is YZ timed as it's applicable to both WR's and YZ's. What does that do to the power delivery of the WR? I have read several posts about the hotcams, and everyone says stuff like "You'll love the power" and "after you install the exhaust cam, you'll love it so much you'll go get the intake cam as well", but what IS the powerband like with these installed?

I do mostly desert, trailrides and am starting to do some DS rides. I'm a mid-fourties, maybe B (on a good day) rider with arthritic knees. I love the power delivery of the WR as it is, and don't really have big enough balls to use all of the power, so I don't want to dork things up by putting in cams that take from the bottom and nice, smooth delivery, and add a big mid-range hit. I would appreciate any feedback both on how the HotCams (both the intake and exhaust) alter your riding experience and powerband, and the tooth profile question.

Thanks, all!

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I beleive i have the most miles with the 03 cam mod in my 01 Wr 426 (10,596 K's) i fitted the cam at 5,720 K's the bike now has a total of 16,316 K's, i am a motor mechanic of 16 years, i think its fair to say that having seen NO visible wear on any of the items related to the cam mod not even valve clearances, that the mod has no reliability issue, "Why" you engineering type ask again and again (no offence) its because of the type of cam chain that Yamaha use, its very forgiving, go on, crack the cover and have a look !

As for the Hot cams i can only go by what i have read here on TT but here is what i know Hot cams has in writing some where here in the archives, Hot cams claimed only a mid to upper inprovement but retaining the same lower end, they are'nt Wr or Yz timed, they are some where inbetween, i will do my best to find this info from Hot cams mouth as such as soon as i have some more time.

I dont know about you folk but i found the bottom end on the 426 to be pretty poor, useless for hill climbs and even worse when your in a corner, left leg out and in the wrong gear with too little revs and 'poof' it stalls and your stopped on the side of the track doing the drill while all your mates are passing you, i know for a fact the 03 cam mod fixes that shit with more bottom end torque, a smoother power curve and auto decomp, you should experience it too, read the top of the Yz forum and go get that cam !!

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HotCams

TT Bronze Member

Join Date: Nov 2002

Posts: 295

Re: YZ 450 cam mod-please read

Hi All,

We do not have WR timming, or YZ timming because these cams are not OEM cams, and need to be timmed differently. YZ, or WR timming only applies to OEM cams. We have designed these cams to be timmed where we found the most usable power with the lobe centers at 105 for both intake, and exhaust , which produces more midrange, and top end power then the stock YZ cams. If you wanted to assocate to one or the other it would be more like a YZ. I hope that helps.

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I'm no ME but the Hotcams adc made a new bike out of the old wr..It was yz timed before and still showed performance increases. Use either cam and you'll wonder how you lived without it, easy starting beast... :cry:

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