first ride with the WR450 cam in my YZ426

14 replies to this topic
  • RogerDedrick

Posted April 05, 2004 - 01:04 PM


Well it s been a long time coming. I finally decided to finish installing the cam this afternoon instead of all the other things that I have been putting infront of the job.
And of course I couln't help getting some gas and giving it a ride.
After the initial many kicks while prbably the carburator was filling with gas it started up and I let it warm up.
I had fun restarting it a few times (first easy kick)
I pulled on my helmet and gloves and went out onto my small flat track area behind the house.
smooth like a sewing machine all the way through the rev range. And I don't think I have done some many wheelies from idle. even in third and forth. chug a chug twist the throttle and up it would come.
I don't think the horse power if off two much from stock as I was running out of braking room about like I am used to. But that mid range lunge is gone. along with the hard wheel spin that came with it. Its just an linear electric motor pull all the way through the rpm range.
Its pretty much what I was looking for as I ride mostly trails and harescrambles.
A very satisfying mod. I think I might go out and kick it over a few more times. :)

  • NuTbAg

Posted April 05, 2004 - 01:26 PM


Well im going tomorrow to get new shims as i think the problem with mine not starting is excessive lift as well as my incorrect timing. :D

I hope my ride goes as well. do you think that just that cam alone is good enough for the type of riding? I'm plaining on installing 13/52 sprockets as well. :)

  • RogerDedrick

Posted April 05, 2004 - 02:36 PM


I have been running the 13/52 in the really tight stuff where I know I will be slipping the clutch a lot. I find if I run the combo on other courses I find myself running in 1st gear near the end of the race when I'm tired and should be in second gear running a little faster. I trred many combinations but have decided on 14/52 most of the time and 13/52 for the one or two tightest courses.
I also am running a 14oz terry cable flywheel weight.

  • Boostn

Posted April 05, 2004 - 03:20 PM


Well im going tomorrow to get new shims as i think the problem with mine not starting is excessive lift as well as my incorrect timing. :D

I think I am in similar boat as you are. I think I know how to time it right. I did manage to start my bike, but the kicks were hard. Not easy as others say. So I am betting my money on the valve shim pads. They are next to impossible to find a shop that carry them in stock. I am in portland, Oregon area. :D :)

  • Matt96xr6

Posted April 05, 2004 - 04:17 PM


When the cam is new, there is little lubrication on all the parts. After installed my 450 cam in the 426, I had the same feelings. Hard to kick past the compression. And yes I used a liberal amount of engine lube.

But not 5 minutes of run time solved that problem! Give it a few minutes to seat in and lubricate all the parts on the cam. Now it starts within half a kick warm.

  • NuTbAg

Posted April 05, 2004 - 04:51 PM


i hope so but you have to admit .06-.09 for gap on exh isn't much so might have had to much down push on valve

  • Fastest1

Posted April 05, 2004 - 07:13 PM


So you ran the WR cam? I had read where the guys racing the 450's were swapping to that cam to smooth the hit and help bottom end. Had you run the YZF cam first? I run the YZF cam in mine and it works great and has for quite a while. I was always curious how the difference would be after the WR cam. Mine rides similar to what you are describing, but that is all personal with out a back to back comparison. Glad you like it!

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • RogerDedrick

Posted April 06, 2004 - 01:32 AM


No I have not run the YZ cam. I'm sure that I am taking a hit on the top end with horse power compared to the YZ cam.
Even the stock 426 cam. Although during the short test ride yesterday I did not feel it. I think it just hooks up a little better without that mid range surge of power.

  • Fastest1

Posted April 06, 2004 - 04:59 PM


Yeah tha is what I had read the pros did it for, was to make the Yzf more tractable instead of explosive! If I would have read that before I had installed my Yz cam I would have tried it too. Good Luck :) Still like the cam anyway!

  • Guest_BrandonV_*

Posted April 08, 2004 - 08:10 AM


Can you tell me what all you ended up buying?
I'm interested in doing the swap on my 2000 YZ426 also and dont have the patience to read 80 pages of the 'official' thread.

  • Fastest1

Posted April 08, 2004 - 04:52 PM


Exhaust cam from a 2003 YZF or WR if you want more bottom end ( that is what I have read about the WR cam). The compression release plug (if you want to eliminate the lever completely, though a guy here on TT makes an aluminum plug that would work better). I bought shims at the dealer after installing it and measuring the clearances. Works great and always has. There is 1 page of instructions that are very detailed and it lists the parts you will need. Shouldnt cost more than 130.00 at the most, for everything! Pm Satch for the link to the instructions. I am too lazy to file all of the things I read here. :)

  • Guest_BrandonV_*

Posted April 09, 2004 - 05:24 AM


Thank you!
You bought the genuine Yamaha 2003 WR450 cam? Aren't there other manufacturer's also and do they offer any advantages?

I already got the aluminum comp plug a few months ago (I knew I'd eventually do this mod) now I just need the cam and probably some shims.

  • Fastest1

Posted April 10, 2004 - 12:31 PM


BrandonV, I am actually running the YZF cam not the WR. I had read that the pros were running the exhaust cams in their YZF's to mellow the hit. It sounded reasonable, Roger seems to be the first person to do so on his older YZF.

  • NuTbAg

Posted April 19, 2004 - 11:44 AM


I went ridding yesterday an i can say it does limit the hit.i would say it depends on what your looking for in your animal but i think im going to try the yz450 cam as i didn't like not having that power move as far off as it did.

I also as well as my friend didn't like the extra noise that it makes now as well.having the exhaust valve open does drop compression but also sounds louder.

I love the way it starts but don't feel it was worth it.
seem to me their are more happy members with the yz450 cam.

  • RogerDedrick

Posted April 19, 2004 - 02:51 PM


The YZ bike is probably not the best bike for the riding I do. Mostly very tight trails which rutted full of roots and slick. And last summer a about 90% mud. I think it may be a better cam for these conditions. Time will tell. I have not had a chance to ride it very much yet. :)

Related Content


Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies

Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  293 replies

Megabomb Fitment by 288yz450

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply

Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride

Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.