Top End Rebuild on a 426

I am rebuilding the top end on my 2000 yz426 and I did not quite understand the timing marks that are on the magnito cover. Can someone please explain this to me... Also, is there certian types of damage I should look for on the head/valves. The jug looks good, I can see the cross hatching on the cylinder. Any tips for installing a " Auto-Decompression Hot Cam"! Thanks for the help....

I don't understand what you didn't understand about the timing mark. I put a topend in my YZ last year and I don't remember it being difficult to understand. Look for any pitting or scaring on your cams. You should check your valve clearances. If they are within spec then you should be fine (and they probably are! Damn Yamahas and their always within spec valves!!!!!) Someone else will have to chime in on the hot cam.

I believe it is the T mark on the flywheel that should be lined up with the notch in the mag cover. Put a new timing chain in while you have the top end a part. The hot cam timing marks are the same as the OEM. It just has a decompression device in the cam. Go to the TT store and order the decompression plug, they have nice anodized units that come with a new seal. Chances are your exhaust valves will need adjusting with the HC, mine did. Good luck with the rebuild. :applause:

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