I'll add more pics as I get them but this one is very clear. I've posted it up very large to make it easy to see but its a perfect example of an indicator of tappet wear that can be observed without removing the cambox.
If you look at the top of the tappet closest to us in the photo you can see that its top sits about 1mm proud of the top of the cambox casting. The one furthest away is flush or maybe even slightly below flush with the cambox casting. This observation is of course undertaken with the piston at TDC compression as if you were checking the valve clearances as at this point both tappets are on the base circles of their respective cams.[You must be registered and logged in to see this image.]
Note that while NOT
seeing this sort of recession does not necessarily mean your tappets are OK if you DO
see it it is a huge alarm siren that you should stop riding the bike and get the cams and tappets examined!