Abstract: A liquid quantity visual confirmation device comprises a first reservoir-forming member, and a second reservoir-forming member forming a liquid reservoir in combination with the first reservoir-forming member. The second reservoir-forming member is at least partially transparent to allow visual confirmation of the internal liquid level from an outside thereof. The second reservoir-forming member has a liquid-feeding port for feeding the liquid into the liquid reservoir. The quantity of liquid in the liquid reservoir can be confirmed by looking at the internal liquid level in the second reservoir-forming member from the outside. It is also possible to reliably feed the liquid into the liquid reservoir from the liquid-feeding port while confirming any rising of the liquid level through the transparent portion.

Abstract: The present invention provides an air-cooled four-stroke internal combustion engine capable of achieving a high degree of cooling. The present invention is directed to an air-cooled four-stroke internal combustion engine including a crankshaft and a fan rotor rotatably driven by the crankshaft to generate cooling air for cooling the engine. The engine comprises an oil pan disposed below the crankshaft. A space formed below the oil pan extends in the axial direction of the crankshaft along the lower surface of the oil pan and allows a cooling air to pass therethrough. An upstream portion of the lower surface is inclined upward, toward the upstream, in a vertical section taken along the axis of the crankshaft to receive the cooling air therein.

Abstract: A liquid quantity visual confirmation device comprises a first reservoir-forming member, and a second reservoir-forming member forming a liquid reservoir in combination with the first reservoir-forming member. The second reservoir-forming member is at least partially transparent to allow visual confirmation of the internal liquid level from an outside thereof. The second reservoir-forming member has a liquid-feeding port for feeding the liquid into the liquid reservoir. The quantity of liquid in the liquid reservoir can be confirmed by looking at the internal liquid level in the second reservoir-forming member from the outside. It is also possible to reliably feed the liquid into the liquid reservoir from the liquid-feeding port while confirming any rising of the liquid level through the transparent portion.

Abstract: The present invention provides an air-cooled four-stroke internal combustion engine capable of achieving a high degree of cooling. The present invention is directed to an air-cooled four-stroke internal combustion engine including a crankshaft and a fan rotor rotatably driven by the crankshaft to generate cooling air for cooling the engine. The engine comprises an oil pan disposed below the crankshaft. A space formed below the oil pan extends in the axial direction of the crankshaft along the lower surface of the oil pan and allows a cooling air to pass therethrough. An upstream portion of the lower surface is inclined upward, toward the upstream, in a vertical section taken along the axis of the crankshaft to receive the cooling air therein.