Rebuilding a 2002 yz426f

I have a 2002 yz426f that im rebuilding the top end on.Just wanted to know if yz 450  cams would work in it an what year cams would i buy if so.

Not exactly.  The problem is twofold. First, the chain tooth profile is slightly different, so even though there have been any number of YZ450 exhaust cams installed in the 426's, it isn't technically "wholesome".

 

Second, the timing marks on 450 cams won't align with anything if used in a 426 head because of changes made to valve angle and location. 

 

But no matter, the aftermarket long ago caught up with the auto decompression thing and people like Hot Cams make exhaust cams that add the AD feature, but drop right in and time just like the originals.  They are now less expensive than the OEM 450 cams, too, so you skate right past both issues.

 

If your original intake cam is in good condition, use it with a Hot Cams stage I exhaust.  If it's looking a little poorly, buy the pair.

Def go with the Hotcams... I jus rebuilt my 01 YZ426 and put in a stage 1 exhaust, dropped right in like stock, and the bike is so easy to start now it's funny. Even easier to kick than both my CRF450r's that also have auto decompression.

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