Cycle changeable engine

A cycle changeable engine capable of changing over its operating cycle to either one of two-cycle or four-cycle operation, comprising:

• a cylinder block;
• cylinder liners, each being fitted into each of cylinders formed in said cylinder block;
• a cylinder head disposed fixedly in said cylinder block;
• first intake ports and exhaust ports, each being formed in said cylinder head;
• first intake valves for a four-cycle operation, each being disposed in each said first intake port;
• exhaust valves, each being disposed in each said exhaust port;
• intake openings formed at lower peripheral portion of said cylinder liners;
• second intake ports formed at the lower port of said cylinder block and communicating with said intake openings;
• second intake valves for a two-cycle operation being disposed in each said second intake port;
• electromagnetic valve driving devices for opening and closing said first intake valves, said exhaust valves and said second intake valves, respectively, by electromagnetic force;
• detection means for detecting the operational conditions of said engine, said detection means including a rotation sensor for detection of the number of revolutions of said engine;
• and
• a controller for opening and closing either one of the groups of said first intake valves and said second intake valves and keeping the other group under the closed state in response to the detection signal by said detection means;
• wherein in response to the detection signal from said rotation sensor representing that the engine speed is a low speed, said first intake valves are kept closed and said second intake valves are opened and closed while said engine is operated in the two-cycle operation.