Stratified scavenged two-stroke engine

A two stroke internal combustion engine comprising:

• at least one transfer passage in gaseous communication between a crankcase chamber and a combustion chamber of the engine,
• an air passage through a crankcase to the crankcase chamber and in gaseous communication with a carburetor of the engine,
• a rotatable circular disk rotatably connected to a crankshaft of the engine,
• at least one first rotary shut-off valve located in a radially outermost section of the circular disk bordered by a periphery of the circular disk and operatively disposed between the transfer passage and the crankcase chamber for opening and closing gaseous communication between the transfer passage and the crankcase chamber,
• at least one second rotary shut-off valve located on the circular disk bordered by a periphery of the circular disk and operatively disposed between the air passage and the transfer passage for opening and closing gaseous communication between the air passage and the transfer passage, and
• wherein the first and second rotary shut-off valves are operably located on the circular disk to close the air passage to the transfer passage when the transfer passage is open between the combustion chamber and the crankcase chamber and to close off the transfer passage between the combustion chamber and the crankcase chamber when the air passage is opened to the transfer passage.