A.fuel valves;exhaust valve B.exhaust valves;inlet valve C.fuel valves;inlet valve D.exhaust valves;fuel valve
A.scavenging air ports;exhaust ports B.inlet ports;scavenging air ports C.scavenging air ports;inlet ports D.exhaust ports;inlet ports
A.open;short;after B.closed;short;after C.open;long;before D.closed;long;before