Four-cycle marine engine

Abstract

Disclosed herein is a four-stroke internal combustion engine comprising a common crankcase, a crankshaft extending in the crankcase, first and second cylinders respectively extending from the common crankcase in acute angular relation to each other and respectively including first and second cylinder walls respectively including first and second exhaust gas discharge ports, a passage connecting the first and second exhaust gas discharge ports, first and second pistons respectively located in the first and second cylinders and respectively connected to the crankshaft for reciprocating movement toward and away from the crankshaft and between top dead center and bottom dead center positions, first and second cylinder heads respectively connected to the first and second cylinders, respectively partially defining first and second combustion chambers, and respectively including first and second mixture inlet passages respectively communicating with the first and second combustion chambers, first and second exhaust gas outlet passages respectively communicating with the first and second combustion chambers, and first and second rotary valves respectively located in the first and second mixture inlet passages and in the first and second exhaust gas outlet passages, first and second primary carburetors adapted to form fuel/air mixtures, and first and second mixture supply passages respectively communicating with the first and second primary carburetors and with the first and second mixture inlet passages and respectively including therein first and second reed valves.