450 Exhaust Cam Upgrade Poll

You've seen the PDF, you've read the posts, now have your vote...

I would like to gauge how many people have done, or are planing on doing, the upgrade...

Remember, you only get one vote per IP address...

<FORM METHOD=POST ACTION="http://www.thumpertalk.com/bike/ubbthreads/dopoll.php"><INPUT TYPE=HIDDEN NAME="pollname" VALUE="1047536342yamaha.dude">

YZ450 Exhaust Cam Poll

<input type="radio" name="option" value="1" />I have a 98-99 WR and have done the cam mod, and love it

<input type="radio" name="option" value="2" />I have a 00-02 WR and have done the cam mod, and love it

<input type="radio" name="option" value="3" />I have a pre-03 WR and have done the cam mod, and hate it

<input type="radio" name="option" value="4" />I have a 98-99 YZ and have done the cam mod, and love it

<input type="radio" name="option" value="5" />I have a 00-02 YZ and have done the cam mod, and love it

<input type="radio" name="option" value="6" />I have a pre-03 YZ and have done the cam mod, and hate it

<input type="radio" name="option" value="7" />I plan to do the cam mod soon, after all I have read on TT so far

<input type="radio" name="option" value="8" />I want to do the cam mod, but the PDF is confusing/too brief

<input type="radio" name="option" value="9" />I'd like to have the cam mod, but I don't think I have the mechanical ability to work on the cams in my bike

<input type="radio" name="option" value="10" />I want to do the cam mod, but it is too expensive

<input type="radio" name="option" value="11" />I'd like to do the cam mod, but I don't like the possible risks involved

<input type="radio" name="option" value="12" />I won't do the cam mod - I don't need no stinkin' auto decompression or more low-end power

<input type="radio" name="option" value="13" />What's a cam mod ? - I have been on Mars for the past 6 months

<INPUT TYPE=Submit NAME=Submit VALUE="Submit vote" class="buttons"></form>



Great idea David, cant wait to see the results in a couple of days.

Just a point, that if we get a few people who want to do it, but are unsure of there ability to do the whole swap, then we (I) may write up some more comprehensive instructions... with more pictures... I can pull my bike apart to use as the model... Please don't answer if you have already done the mod...

So, for you guys with 2 left hands and 10 thumbs...

<FORM METHOD=POST ACTION="http://www.thumpertalk.com/bike/ubbthreads/dopoll.php"><INPUT TYPE=HIDDEN NAME="pollname" VALUE="1047546949yamaha.dude">

Would you have a go...?

<input type="radio" name="option" value="1" />Yes, I would have a go at it myself with more comprehensive instructions

<input type="radio" name="option" value="2" />Yes, I would have a go if a fellow TT'er was watching and guiding me

<input type="radio" name="option" value="3" />I like fences, I am sitting on one now, just waiting to be pushed...

<input type="radio" name="option" value="4" />No, I will just take it to the dealer and get them to do it eventually

<INPUT TYPE=Submit NAME=Submit VALUE="Submit vote" class="buttons"></form>


As for the 'too expensive' guys, and the 'possible reliability issues' guys, well, presume, when you choose an option, that you are getting the cam and shims (inc. S & H) for that price, or that the third-party cam is guaranteed to work 100% reliably, and will be available in 3 to 6 months time.

<FORM METHOD=POST ACTION="http://www.thumpertalk.com/bike/ubbthreads/dopoll.php"><INPUT TYPE=HIDDEN NAME="pollname" VALUE="1047547969yamaha.dude">

Let's talk hard currency...

<input type="radio" name="option" value="1" />I would do the mod if it was below US$100

<input type="radio" name="option" value="2" />I would do the mod if it was below US$150

<input type="radio" name="option" value="3" />The local dealer is gouging me hard, and I can't find one anywhere else for a decent price

If reliability issues worry you, then...

<input type="radio" name="option" value="4" />I'll consider the mod when more people have more reported miles on their bikes...

<input type="radio" name="option" value="5" />I would pay up to US$100 for a third-party cam

<input type="radio" name="option" value="6" />I would pay up to US$120 for a third-party cam

<input type="radio" name="option" value="7" />I would pay up to US$150 for a third-party cam

<input type="radio" name="option" value="8" />I would pay over US$150 for a third-party cam

<INPUT TYPE=Submit NAME=Submit VALUE="Submit vote" class="buttons"></form>


Nice poll, David.

For those of you concerned about the chain wheel to chain fitment, Web Cams claims to be developing an auto deco performance grind cam that will mesh properly with the 400/426 chain. I will get one for my own use if they actually do become available, and give you "fence sitters" feedback along with dyno results.


auto bump...

Can't seem to pin it to the top, so another bump...



Just a quick update... I have gotten to about 1000 km's on the 450 cam, decided I would pull the cover off and check the clearances... they were absolutely the same as the day I installed the cam... no noticeable wear on the cam sprockets... I used an 8 x magnification to view the teeth... no wear on the cam lobes, the bucket faces, or the bearing surface... chain feels nice and tight...

I don't think I am going to have any long-term issues with this mod... Just wanted to provide an update to those interested...



Just got done doing the initial install. Now I just have to order and wait for the new shims... Stock exhaust were #171 and #174. According to the chart, I will need a #190 and a #195 with the new cam. I hope that jives with what everyone else is reading.

This was the first time the valve cover has ever even been off this engine. I found the most difficult part was getting an accurate measurement with the feeler gauges. Pretty tight in there, especially on the three intake lobes, and spending a whole day trying to find metric off-set gauges was a complete waste of time. The ones I used are SAE marked in thousandths with metric equivilents marked on them. Upon examining the shim chart, they provide an acceptable range of values.

I was surprised how tight the tolerances were from the factory on both the intake and the exhaust sides! Right at 0.25mm on the exhaust and 0.15mm on the intake; almost had to force the gauge in.

I would be more comfortable with something in the middle of the range, but won't mess with the intake side since it has obviously been running fine at the tight-end since the bike was new. If anything, I guess I expected to see the measurements more to the loose side since wear would only increase them. Must not be wearing at all. Mobil 1. :D

I started with the stock WR timing and had 13 pins between the dots on the gears. With the YZ450 cam and timing, the exhaust dot is not straight up, and I now have 14 pins between the dots. Everything looks just like the pdf file pics. There is no slack in the chain between the exhaust gear and crank gear. All the slack is on the crank gear-to-intake gear (slack adjuster) side, as it should be.

At first, the gear teeth on the 450 cam look significantly different. But when you compare how the chain meshes on the stock intake gear side-by-side with the new 450 gear installed, it is not much different.

I have taken digital pics of every step of the procedure if you want them, David. It would save you an extra teardown of yours if you plan to make a set of more complete instructions. I would have to email them to you as I haven't ever done the web-hosting thing... and you know how I am with computers... :D

This has not been very difficult. One thing: do not pay any attention to the factory manual where it shows which is the intake and which is the exhaust cam. In my manual, they have it backwards :D. You really can't screw it up anyway, but you might remove your intake cam needlessly.

Right now I am going to do the Jamesnow mod. If anyone has a good suggestion for jetting this '99 400 motor with the 450 cam, Big Gun tapered exhaust, and Jamesnow; I would appreciate getting in the ballpark on the first attempt.

Thanks to all who have made this possible! :)

Good to hear... Sounds like you are going to be happy... It will make a difference to the bike... I cannot offer any specific jetting advice for your big gun pipe, but the JamesNOW! and the cam mod really mad no difference to my jetting... I think I twiddled with the fuel screw a half turn either way to see, but it runs fine as it was before the mods...

You may have to let us know if you have any miss, bog or other issues once the beast is fired up... we can then help you better... you may want to go to the YZ needle of that year your bike is, as you are going to YZ timing from WR... I did the same. put the cam in and went to YZ timed in the one step... hope your wheelstand skills are up-to-date... LOL

Good to hear your valves were in spec as well...

I also went looking for a set of metric feeler gauges, ended up with a 35 blade set from Snap-on that were both inch and mm... but at least they went down thin enough to measure the sort of tolerance the manual talks about...

You could send me the pics if you like... I pulled mine apart yesterday actually to check the clearances at 1000km... going to clean the carb today and see what else I can do while I have the tank off... headstem is getting done again... while the forks are off, I may change the fork oil... I was thinking 2.5W...

good luck with the JamesNOW! it is the perfect compliment to the 450 cam... I did not cut the sides of my housing, but I did cut a slot in the rear to hold it... I just slightly creased the middle of the plate, and once it was in, located by the grooves at the airbox end of the intake bell... I then pressed down and the thing holds itself in place with the natural spring tension of the metal...



Thanks, David!

I really AM pumped! Can't wait!

I'll order the YZ needle along with the shims tomorrow AM. I really like your JamesNOW! method and will try that. A couple of short slots at the airbox side would be sufficient for any locating issues.

I am fortunate to have a good friend who is a Snap-On dealer. After checking several stores yesterday, I gave him a call and drove the 35 miles down to his house to pick up what sounds like the exact set you used. He gets me anything for his cost, and in cases like this, I think even less than 'cost' sometimes! We met in the same way I have met so many good friends the past five years: Our sons are racing competitors and friends!

The head-bearing issue is one I plan to address soon along with the linkage by doing like Taffy and installing grease zerks! I have been doing this to my sons' bikes for years and it really works! Amazing how much water comes out when you re-lube after washing the bike, no matter how careful you were!

As for the wheelies: Yikes! I love to do 'em! I WILL, however, remove my new UFO taillight/fender extension first! The REAL test will come when I have a young phenom A-class racer named Kurt McCabe give'er a "test ride". I love watching him "teach" my old dog new tricks! :D I have video footage of him doing an 80'+ triple on the big beast in full street/stock trim (while someone off-camera says "Wow, Skyler, look at your Dad fly!!") :D He is a superfast local kid who befriended my boy and boy can he ride!! It amuses me that he just loves to ride my big heavy 4-slow-poke! "Funnest thing with turn signals he ever tried!" :D The new mods ought to really surprise him!! :):D :D Gotta get the suspension done next... It's pretty cool seeing what my bike is really capable of, even if I'm not!

The set I got was Part No FB335... the metric set, FBM320 only increments in .05 mm... the imperial set I have has one inbetween... approx .025mm... they are stamped with mm, so no problem reading them...

I wish I had a Snap-On dealer as a friend... the guy in the truck is friendly, but I asked him for a discount once and he said he would have to do it for everyone... :D :D

Are you planning to drill the grease fitting right through the bearing races...? I was looking at that, but wondered about delivering the grease to where it is most needed...

Have fun, you won't have to buy a front tire for a while... they never wear out... maybe a rear fender though... :)

The little slots in the back of the intake tract are just to stop it twisting... you could add a dab of stuff to it to glue it in place... I files a couple of saw shaped 'teeth' on each side, so it does sort of bite into the plastic... not much, but enough to keep it from acting like a reed valve... LOL



Great Poll. I'm in the "plan to do category" and I see a few others (3 so far) have done it to their 98-99 WR/YZ's. Any comments on reliability so far would be greatly appreciated.

Interesting results so far, keep the votes coming...


just keeping the poll alive and in your faces... :):D


Only 93 votes, these guys are dead eh, David??

0.0% installed the cam and disliked it. That's no surprise. :)

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