wr 450 lower end with a yz 450 top end?

5 replies to this topic
  • skoke70

Posted January 18, 2008 - 06:02 PM


I should probally have done a little more research before posting this but what the heck, I have a friend thats parting out his 04 wr 450. I was thinking of buying his engine and using the lower end along with my top end off my 04yz 450. the reason is I would love to have the 5 speed and I also would love to hook up a head light which the wr's lower end would give me. Is this possible? has anyone done this before?

  • grayracer513

Posted January 18, 2008 - 09:44 PM


What year are the two bikes? The exchange you want to do is possible if the YZ is an '03-'05, and the WR is an '03-'06. It is also possible if the YZ is an '06-'08, and the WR is an '07-'08. Unless your YZ is an '03, you'll need a clutch cable for the WR, but otherwise, it should fit right together.

  • Kent Rathgeber

Posted January 18, 2008 - 09:48 PM


Would it be easier to put the WR tranny (or 5th gear) in the YZ and go with an aftermarket light kit?? The reason I ask that is because there is the possiblility that the motor mounts and head stays might not be in the same place on the YZ. Grayracer, whadda you think?

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  • grayracer513

Posted January 18, 2008 - 10:33 PM


The steel WR/YZ's both use the same mounts and stays, so that's a non-issue. The trans can be transplanted into the YZ crankcases, but the WR generator assembly can't. That will only work with the WR cases.

I would have done this to my '03 in a heartbeat if I had had the chance.

  • skoke70

Posted January 18, 2008 - 11:30 PM


Great! They are both 04's. Looks like I got myself a winter project.
Thanks guys:thumbsup:

  • SXP

Posted January 19, 2008 - 11:29 AM


I'm pretty sure you are going to need the WR CDI box, in which case you might need the wiring harness too. I have a sneaky feeling it's going to be a little more complicated than just the top end/bottom end mix and match. The electronics/electricals are going to complicate things.

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