The crankcase is a standard 2-stroke, but instead of pushing air/fuel mixture into the cylinder, only fresh air is pushed in.
The revolutionary new design is in the head. There is a tiny crankshaft operated by a belt that operates a small piston, it first sucks in a very rich air/fuel mixture into this small cylinder. It then gets compressed to over 65 PSI. Then a small spring valve (the intake valve) opens up as the main piston is nearing top dead center. Once the air/fuel mixture is ignited the spring valve closes.