Abstract: A cylinder head of an internal combustion engine includes a cylinder head main body which is formed with a main body side plug insertion hole into which an ignition plug is inserted, a cam holder which is fixed to the cylinder head main body and forms cam bearing portions together with the cylinder head main body, wherein the cam bearing portions rotatably support an intake camshaft and an exhaust camshaft, respectively, and wherein the cam holder is formed with a holder side plug insertion hole which communicates with the main body side plug insertion hole and into which the ignition plug is inserted, and a knock pin which is disposed across the main body side plug insertion hole and the holder side plug insertion hole to restrict assembly positions of the cam holder and the cylinder head main body.

Abstract: To provide sensing system layout structure of an internal combustion engine that enables increasing a degree of freedom in laying out a sensing system. In sensing system layout structure of an internal combustion engine provided with a sensing system for sensing rotation of a camshaft, the internal combustion engine is provided with a driving shaft rotated in synchronization with the camshaft, the sensing system is provided with a driving shaft rotation detecting sensor arranged opposite to a rotated portion on a side of the driving shaft, and rotation of the driving shaft is sensed by the driving shaft rotation detecting sensor.

Abstract: An oil strainer support structure for an internal combustion engine capable of improving the maintainability of an oil strainer is provided. In an oil strainer support structure for an internal combustion engine having an oil strainer, the oil strainer is supported by a drain bolt provided in the internal combustion engine. The oil strainer can be detached by removing the drain bolt to improve maintainability.

Abstract: To provide sensing system layout structure of an internal combustion engine that enables increasing a degree of freedom in laying out a sensing system. In sensing system layout structure of an internal combustion engine provided with a sensing system for sensing rotation of a camshaft, the internal combustion engine is provided with a driving shaft rotated in synchronization with the camshaft, the sensing system is provided with a driving shaft rotation detecting sensor arranged opposite to a rotated portion on a side of the driving shaft, and rotation of the driving shaft is sensed by the driving shaft rotation detecting sensor.

Abstract: An oil strainer support structure for an internal combustion engine capable of improving the maintainability of an oil strainer is provided. In an oil strainer support structure for an internal combustion engine having an oil strainer, the oil strainer is supported by a drain bolt provided in the internal combustion engine. The oil strainer can be detached by removing the drain bolt to improve maintainability.

Abstract: A cylinder head of an internal combustion engine includes a cylinder head main body which is formed with a main body side plug insertion hole into which an ignition plug is inserted, a cam holder which is fixed to the cylinder head main body and forms cam bearing portions together with the cylinder head main body, wherein the cam bearing portions rotatably support an intake camshaft and an exhaust camshaft, respectively, and wherein the cam holder is formed with a holder side plug insertion hole which communicates with the main body side plug insertion hole and into which the ignition plug is inserted, and a knock pin which is disposed across the main body side plug insertion hole and the holder side plug insertion hole to restrict assembly positions of the cam holder and the cylinder head main body.

Abstract: An oil filter layout structure for an internal combustion engine for a motorcycle. An exhaust pipe connected to an exhaust port extends rearwardly beneath the internal combustion engine along a longitudinal direction of the motorcycle. An oil pan is disposed below the internal combustion engine, the oil pan having one of left and right side walls spaced along a transverse direction of the motorcycle. The one side wall is inclined downwardly toward a center of the motorcycle. The exhaust pipe is disposed closely to the side wall. An oil filter is mounted on the internal combustion engine and disposed below the internal combustion engine in overlapping relation to the oil pan as viewed in side elevation, near the other of the left and right side walls of the oil pan.

Abstract: A water-cooled engine includes first connection paths continuous with a cylinder-head-side water jacket and a second connection path continuous with a cylinder-body-side water jacket. The paths are disposed in a sidewall of a cylinder body. A thermostat valve is attached to the sidewall. An oil cooler having a cooling water lead-in pipe and a cooling water lead-out pipe is attached to one sidewall of an engine main body to face the same direction as that of the thermostat valve. The cooling water lead-in pipe and the cooling water lead-out pipe are connected to the thermostat valve.

Abstract: An oil filter layout structure for an internal combustion engine for a motorcycle. An exhaust pipe connected to an exhaust port extends rearwardly beneath the internal combustion engine along a longitudinal direction of the motorcycle. An oil pan is disposed below the internal combustion engine, the oil pan having one of left and right side walls spaced along a transverse direction of the motorcycle. The one side wall is inclined downwardly toward a center of the motorcycle. The exhaust pipe is disposed closely to the side wall. An oil filter is mounted on the internal combustion engine and disposed below the internal combustion engine in overlapping relation to the oil pan as viewed in side elevation, near the other of the left and right side walls of the oil pan.

Abstract: A water-cooled engine includes first connection paths continuous with a cylinder-head-side water jacket and a second connection path continuous with a cylinder-body-side water jacket. The paths are disposed in a sidewall of a cylinder body. A thermostat valve is attached to the sidewall. An oil cooler having a cooling water lead-in pipe and a cooling water lead-out pipe is attached to one sidewall of an engine main body to face the same direction as that of the thermostat valve. The cooling water lead-in pipe and the cooling water lead-out pipe are connected to the thermostat valve.