May have found & solved the problem!

Basically as you can see I split the case after the scored piston and air leak which happened midway through a ride last Sunday. The case was split in about 30 mins as I'm quite familiar with splitting it. When inside, I found what can only be described as something that looked like a floor of a Blacksmiths work shop. Pieces of metal from both pistons sat at the bottom of the case! Anyway it's been cleaned out and reassembled ready for the 3rd piston of this engines very problematic start to its 70cc life!