wr 450 lower end with a yz 450 top end?

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?


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.

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?

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.

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

Thanks guys:thumbsup:

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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