Patent ID: 8689752

Claim:
A vertical-type air-cooled OHV engine, comprising: a valve operating system configured to drive intake and exhaust valves provided in a cylinder head to open and close, said valve operating system comprising: a camshaft arranged parallel to a crankshaft supported by a crankcase in a vertical attitude, said camshaft being rotationally driven by the crankshaft; intake and exhaust pushrods that are disposed on one side in a cylinder block and the cylinder head relative to an axis of a cylinder bore of the cylinder block, said pushrods being driven to be lifted and lowered by the camshaft; and intake and exhaust rocker arms that are pivotally supported by the cylinder head to open and close the intake and exhaust valves in conjunction with the lifting and lowering of the intake and exhaust pushrods, the vertical-type air-cooled OHV engine further including: a cooling fan attached to and driven by the crankshaft, a shroud guiding cooling air, generated by the cooling fan, such that the cooling air flows in an up-down direction with respect to the cylinder head, wherein the intake and exhaust valves are arranged respectively on opposite sides of a vertical plane which is parallel to an axis of the crankshaft and which includes the axis of the cylinder bore of the cylinder block, wherein the intake and exhaust rocker arms are formed to have different lengths depending on a distance between the intake pushrod and the intake valve and a distance between the exhaust pushrod and the exhaust valve, a longer one of the rocker arms is formed to be bent such that a center portion thereof pivotally supported by the cylinder head is offset outward from opposite end portions thereof, and an included angle formed between the intake and exhaust valves is such that a distance between the intake and exhaust valves becomes greater toward valve stem ends thereof.