Schnuerle ported engines have a flat top piston (piston without baffle on top) and typically a dome combustion chamber with a squilsh band around the edges.

On each side of the exhaust port are the main intake ports directed towards the back of the combustion chamber.

Opposite the exhaust port there is usually (but not always) a boost intake port.

Schnuerle engines have superior throttling characteristics to the loop scavanged engines. They often produce more power and have better economy as well.

Jim