Two-stroke internal combustion engine with cylinder head valves

A two-stroke internal combustion engine comprising:

• a cylinder block and a cylinder head mounted thereon to form a combustion chamber therein, said cylinder head having at least one intake port and at least one exhaust port formed therein, with an intake valve and an exhaust valve being arranged in said at least one intake port and said at least one exhaust port, respectively, for operation in synchronization with the engine to open and close the respective port;
• a fresh air intake passage means having an air charging means arranged therein for delivering fresh air under pressure to said at least one intake port;
• means for generating a swirl about an axis of said combustion chamber by a portion of exhaust gas caused to flow back from said at least one exhaust port into said combustion chamber after once being exhausted through said at least one exhaust port when said exhaust valve opens;
• a tank means having a connection passage in communication with said fresh air intake passage means at a position downstream of said charging means;
• and
• a valve means arranged in said connection passage and closing said connection passage when the engine is under a relatively high load.