YZ450 exhaust cam upgrade - Opinions Needed

Great idea David! :)

It is worth doing for the auto decompression feature. I love the way this bike starts with the rear wheel when locking up the rear and releasing it in a corner the bike fires up like a 2 stroke. This is by far the most advanced 4 stroke trail bike ever. Not to mention the front forks are the best handling forks I have ever had on the trails. Yamaha really out did themselves with the WR450. The cam mod is worth every penny. :)

The question is do you want the WR450 Cam or the YZ450 cam.

Personally I like the WR cam bottom end much easier to pop the front end up without the clutch when crawling to get over large obstacles. It is also better in tight woods. The YZ cam has a great midrange acceleration when you get to more open areas. I may go back to my WR cam. Waiting for my TA pipe to see if it picks up the YZ cam bottom end. :)

Am I correct in assuming that I can put an '03 WR exhaust cam in an '01 WR426, then?

Or I could put in a YZ cam instead?



Read an article about cam on the WR450 having a different pitch in the cam chain compared to all the other YZ/WR's and though, it would interchange, rapid chain wear would occur. I was about to get a WR450, but after reading some of the troubles, I'm leaning on getting a WR 426, and being used, can save lots of $$$ anyway. Should I wait for the refined WR 450, go with the 426??? A clean WR 400 would even be OK too, but I really want the displacement!

FYI, Hot Cams is in pre production tresting of a aftermarket auto decompression ex cam. It will be available soon.


I have read that you can't put a 450 cam in a 426.

I have switched my '03 WR450 cam for an '03 YZ450 cam. After the switch, my bike is harder to start. Other than that it runs smooth. Has anyone else experienced this problem?

I did the YZ cam upgrade. The bike is hard to start now. Could I have done it wrong? I did the procedure just like the service manual said it should be done. I carefully checked the cam before I put it all back together. I actually marked the timing chain (with a magic marker) exactly where the WR cam's markings were. When I put the YZ cam in I used the same spot for the one that lines up with the top of the head (the left hand side mark). The top mark on the cam did not go in the exact same spot; that mark is 1 tooth to the right (closer to the intale cam). There were 14 timing chain pins between the top cam markings before the change, there are 13 pins between after. If anyone has done the upgrade sucsessfully, would they mind letting me know if this is right? :)

OK that's right. Jetting is the next project.

:D:):D :D

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