Just got in from testing it out. Opened the HSN about half a turn or so and it ran a little bit better but still lost some rpm on WOT. Still got very hot after each run and the compression was lost, but returned as it cooled. I noticed that as you turn it past compression it feels like there is a second compression or resistance as the piston goes back down past the exhaust outlet. I took the glow plug out and there was no feeling of the pinch at the top of the stroke. Not sure if TT engines are supposed to have that or not.

So I let it cool and took the top of the cylinder off to see what I could. The top came off rather easily, by which I mean it turned and slid right out. The piston and liner were clean but one "quadrant" of the piston and associated liner were black, almost like they were burned. There was a matching mark on the cylinder top, almost like something leaked out.

Question: is there supposed to be some sort of gasket between the cylinder and the top? Right now it's just metal on metal.

Thanks!