| 摘要 |
PROBLEM TO BE SOLVED: To provide a cooling structure of a forced-air-cooled four cycle engine capable of selectively cooling a specified position of the engine. SOLUTION: In this cooling structure of a forced-air-cooled four cycle engine wherein a plug attaching seat 18 is disposed between an exhaust port 16 and an intake port vertically opened to a cylinder head 9, the whole of the engine 1 is covered with an air shroud 24, and a part of the engine is forcibly cooled with cooling wind led into the air shroud 24 by a cooling fan 21 rotated coaxially with a crankshaft; an inclining surface 24A inclined toward a specified position (a diagonal line part) of the engine 1 is formed on the air shroud 24, and a flow passage cross section of the air shroud 24 is throttled toward the specified position. Cooling wind is concentrically supplied to the specified position (a region including an exhaust pipe attaching part to the exhaust port 16 and the plug attaching seat 18 having a high temperature) of the engine 1, and the specified position is selectively cooled with a good efficiency by cooling wind.
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