| 摘要 |
There is provided a multicylinder four-cycle combustion engine, in which a communication hole is formed, to allow gases to flow smoothly form one cylinder to another so that the pumping loss occurring within the cylinders can be reduced. The combustion engine (E) includes an engine casing (EC) having defined therein a plurality of cylinders ( 2 A to 2 D), each having a cylinder bore ( 20 A to 20 D), and a crank chamber ( 30 A to 30 D) below the respective cylinder bore. A partition wall ( 21 ) separating the neighbor cylinder bores ( 20 A, 20 B; 20 C, 20 D) of the cylinders ( 2 A to 2 D) and the crank chambers ( 30 A to 30 D) from each other is formed with a communication hole ( 4 ). An open edge portion ( 4 aa) of the uppermost edge ( 4 a) thereof, which opens into the cylinder bore ( 20 A to 20 D) has a circumferentially intermediate major portion extending in a direction substantially perpendicular to the cylinder longitudinal axis (CH).
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