just a quick bit of info for any one needing to no how to adjust the pv on your cylinder after having it over bored mines 57.67 now and the piston and rings hit the pv !
so when you get ya barrel back bench it and assemble it all as normal then with the pv in the closed position use a bright coloured marker to draw on pv on the area needin modding, pic 1 shown in red!
then remove the power valve and it exposes the area needing a fettle seen in pic 2
you can either use a dremel. die grinder with a carbide burr or a file
while removing material keep installing the pv halfs now and again until you have removed enough of the surface to have 1mm clearance from the piston/rings
just thought as well i bet the person at the shop told me i could only have one more rebore on my bike because it will start hittting the p valve if i have anymore i can hear a clunk every so often top end is comin of today 2 moz examine if its damaged theres a 100 quid down drain if it is genuine yam piston =-(dead
From my experience with rebores etc etc, these garages ESPECIALLY my local yamaha dealer tend to forget about the powervalve bit etc etc, trial and error really I suppose, we do learn the hard way :-S
Another thing people overlook is that when having an overbore done, the head gasket needs reaming out,as well as having the power valve ground to suit.
