Yz426/wr450 cam swapping

Hi, does anyone know if either or both cams from an 05 Wr450 will work in a yz426? Looking for auto decompression and a mate is selling them cheap. Tia

Edited by mattyvd69

Yes on the exhaust cam. Common upgrade exactly for your reason. Not sure about the intake; I would imagine yes for it as well.

Because the 450 cam was made for a head with different valve angles and other differences, the OEM timing marks don't work.  The only way to get the 450 exhaust cam timed outside of trying to eyeball the lobe position is to use the properly timed intake as a reference.  The intake is timed, then you count pins between the 12 0'clock marks to set the exhaust. 

 

Because of that, you can't use both cams unless you plan to time them with a degree wheel instead of by their marks.

 

Read:

 

http://www.thumpertalk.com/topic/56257-yz-450-cam-mod-please-read/page-49#entry2979654

 

and:

 

http://www.thumpertalk.com/topic/56257-yz-450-cam-mod-please-read/page-53#entry4458141

 

You also cannot modify the exhaust cam timing between YZ and WR specs simply by moving the cam one tooth as you can with the non-auto decompression cams because the AD mechanism is cam timing dependent, and if you retard the WR cam to YZ timing, the decomp pin will hold the exhaust valve open until after TDC, and you won't have any compression to start the bike with.  If you use the WR450 cam, you'll drop between 5 and10 horsepower versus the YZ426.

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