2007 Wr450 top end swap 2009 Yz450f


So i currently have a 2009 Yz450f and a 2007 Wr450f. Im just getting ready to retire out of offroad racing and continue doing my thing with Rescue 3 by using only the Wr. What im looking to do is Taking the 2009 Yz450f top end and throwing it on the 2007 Wr. i have a brand new cylinder, head, valves and piston on the 09 Yz and i dont want to loose my ass selling the bike with all that on it. so my plan is to do the swap and part out what ever is left of the Yz and wr top end. Will everthing be compatible? Will it also give the Wr some more power?

Well, it will all bolt into place, but....


The cylinder and piston are interchangeable.  Both bikes use the same stuff.  The head offers a minor improvement in port layout, but there's no place to plug in your AIS system, required by California. 


The cams will give the bike more power, but you'll have to spend some time getting the electric start to work with them (search this forum).  The carb would be a good addition, but the YZ won't like the WR carb at all, and again, the YZ carb will cause trouble with the AIS system if you decide to keep that. 


After you get the WR running, if you've transferred all that good stuff to it, you'll need to think of some good excuse as to why your YZ is such a slug. 

Save your time effort and money and just put a good tuneable ignition system on the WR, and you will be much happier.

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