Cylinder cooling apparatus for air-cooled engine

A cylinder cooling apparatus for an air-cooled engine, the apparatus comprising:

• a crankshaft extending in an axial direction;
• a cooling fan provided on one end section of the crankshaft;
• a cylinder having a cylinder bore and an outer circumferential wall;
• a cylinder head connected to a top surface of the cylinder;
• a pair of pushrod insertion holes for air intake and exhaust valves, the pushrod insertion holes being spaced apart in the axial direction of the crankshaft and being disposed in the outer circumferential wall of the cylinder;
• a fan shroud covering the cooling fan;
• a cutout ventilating section formed in the outer circumferential wall of the cylinder and located between the pair of pushrod insertion holes;
• a tunnel-shaped ventilating hole formed in the outer circumferential wall of the cylinder and disposed between one of the pair of pushrod insertion holes closest to the fan and the cylinder bore, the tunnel-shaped ventilating hole extending from the outer circumferential wall on the side of the cooling fan to the cutout ventilating section;
• and
• a gasket sandwiched between the cylinder and the cylinder head,
• wherein the cutout ventilating section and the tunnel-shaped ventilating hole are disposed on an opposite side of the gasket from the cylinder head.