APV hit piston?

[ped]

Can power valves hit piston/rings? I have put in a new top end on my sled because on PTO side the piston had a bunch of score marks on it, it was mainly on exhaust port side, but carb side was not clean by any means. My guess is piston slap due to bad rings/ to much clearance. or else a bit of a cold seize but the funny part is that mag side piston looked like new? so cold seize don't make much sence. I don't think it is a lubrication issue. any help would be great hope to post pictures in a day or so
thanks

 

[RACINSTATION]

Unless the valves are in upside down (possible on M6, M7, older M8s/ Not possible on the M1000 or newer M8) you could cause damage. Based on your description it sounds like a lean seizure. The PTO side runs leaner and if you have mods that may be exaggerated.