He uses amsoil, What else would of causes it? I will add a picture of the piston to my pics (elavation was about the same)

 

maybe I missed it, but are we overlooking the obvious? lean jetting, high compression with lower octane fuel? maybe he was on the lean side and it got a little hot and melted a piston. wouldn't be the first time.

i'll see if i can find the pic of the piston. where the hell do i go to see your pics anyway, this place links different than i'm used to.

 

My Pic are waiting approval.

The jetting looked good, He has ran the same jetting for 8 months (about 75 hours of use). (But anything is possible)