Its a good mod and will give a little more to the bike even better if you have a reprofile at the same time but thats only if you have a tune other wish just a skim. It just razers the compreshon. People say Its a mod you can notice when done.
I would measure the piston / head clearance and take it down to about 1.25 to 1.3 mm this if I remember right is spot on for road use and still 100% reliable. Dont do what I did and try to skim it yourself could not get it flat enough but took it to a car engineers place and they did it for £15. Pete
i think you can go down to around the 1mm mark without too much worries but the thing is if you do go too far...boooom! seriously though,skimming the head is one of the easiest ways of getting more power but you need to start by measuring the actual clearance you have before you start.the tolerances on these old bikes were sometimes a bit hit and miss.