The fuel is 10 percent nitro, 18 percent coolmaster mixed fresh. Prop is an 11x8. Plugs OS no.8.

I further ran the engine but it never did pick up it's compression. I'm not sure why but I have had very little to do with ringed two strokes before. Plenty of time on ringed four strokes and dozens of ABC's.

It was run in as carefully as any of my previous engines strarting splutteringly rich at first and leaning out over time.

As I am too far, and the engine is too inexpensive. i won't really consider sending the engine in. So I have pulled it down for a look before putting it in the cupboard for parts. the only thing I have noticed is uneven polishing from a clearly out of round ring or bore, the non-polished areas having a bronze effect. Everything else seems in order, the ring sits in it's land, and is not cracked or missing a piece. The piston top has a small hole where the pin to stake the piston ring has clearly been pressed through.
Rod is fine, everything looks fine (nicely engineered these days the internals too). So all I can guess is a poorly sealing ring.