450 ex cam swap into 426 shim help

OK, I got a 03 yz ex cam to put in my 02 wr426. I would like to install and shim it without running to the Yamaha shop once I get the readings. I see hot cams have shim kits but I have no clue which set to order. Any idea which set would be best??

Also, I’ve read a few threads on this subject but the answers bounce back and forth. :) Can I install the cam with the timing mark lined up (wr timing?) or does it have to be installed one tooth counterclockwise (yz timing?)?

BTW I just installed the Rekluse auto clutch, that thing is the nads! :D

If it is a YZ cam it must be installed with YZ timing. If you install it with WR timing it will not start. This has to do with the auto decompression weights on the cam

Yamaha, thanks for the confirmation. I just wanted to make sure, I just trail ride so I'm installing the cam for ease of starting not for more power and didn't want to YZ time it if it wasn't necessary. Although I hear it also hear it evens out the power band when installed with the WR intake cam.

Any one have advise on what shims to order?? :)

The powerband seems a little smoother with the 450 cam YZ timed than my old 426 cam YZ timed. I think you will like it. I'm able to just give a little kick and it fires right up.

OK, I've been looking for 2 hours on the site now. Can anyone point me to some detailed directions (i.e. written and pics) for doing the YZ450 decomp mod to my 01 WR426. I was looking at Hotcams, but their instructions were difficult for me to understand at best. Since this will be my first crack at engine work, I need to be very clear on what I'm doing or I won't attempt it. I appreciate it fellas.

chips23. I have a PDF of the install instructions. Shoot me an email at dkearns@mazdausa.com and I will attach to the reply :)

I installed the cam today and I like it a lot :) Not only easier to kick over but the response down low is awesome :) I come up on a water crossing or a rut and I just blip the throttle and the front comes right up. Almost the response of a 2 smoker :D

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now