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: 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 internal combustion engine includes a crankcase, a case cover for covering a side of the crankcase, a crankshaft and a balancer shaft. A balancer has a balancer driven gear and a balance weight provided on the balancer driven gear and is acted upon and driven by a driving force of the crankshaft to rotate. An oil pump is accommodated in the crankcase and has an oil pump driving shaft disposed in parallel to the crankshaft and the balancer shaft. The oil pump includes a pump driven gear. The balancer has a pump driving gear which has a diameter smaller than that of the balancer driven gear and rotates together with the balancer driven gear. The pump driving gear meshes with the pump driven gear. The oil pump driving shaft is disposed within a range of rotation of the balance weight as viewed in an axial direction thereof.

Abstract: An internal combustion engine includes a crankcase, a case cover for covering a side of the crankcase, a crankshaft and a balancer shaft. A balancer has a balancer driven gear and a balance weight provided on the balancer driven gear and is acted upon and driven by a driving force of the crankshaft to rotate. An oil pump is accommodated in the crankcase and has an oil pump driving shaft disposed in parallel to the crankshaft and the balancer shaft. The oil pump includes a pump driven gear. The balancer has a pump driving gear which has a diameter smaller than that of the balancer driven gear and rotates together with the balancer driven gear. The pump driving gear meshes with the pump driven gear. The oil pump driving shaft is disposed within a range of rotation of the balance weight as viewed in an axial direction thereof.

Abstract: A crankcase of an internal combustion engine with a reduced size for an oil pan. A crankcase is composed of an upper crankcase half and a lower crankcase half. A wall portion for defining a space X as a flow passage for a lubricating oil is formed below a journal bolt mounting surface of the lower crankcase half. A tool insertion hole for insertion of a tool for tightening a journal bolt is formed through the wall portion.

Abstract: A crankcase of an internal combustion engine with a reduced size for an oil pan. A crankcase is composed of an upper crankcase half and a lower crankcase half. A wall portion for defining a space X as a flow passage for a lubricating oil is formed below a journal bolt mounting surface of the lower crankcase half. A tool insertion hole for insertion of a tool for tightening a journal bolt is formed through the wall portion.

Abstract: An accessories arrangement structure for an internal combustion engine for securing a banking angle, increasing a degree of the freedom of the layout, concentrating heavy accessories and an overhanging part of the internal combustion engine, enhancing the maneuverability of the vehicle and reducing the size of the engine. An accessories arrangement structure of an internal combustion engine for a motorcycle includes an oil cooler and an oil filter that are attached together with a balancer in a lower part wherein the front of a crankcase that journals a crankshaft directed in a vehicular width direction, in which the oil cooler and the oil filter are attached to the front in a vehicular traveling direction of the crankcase project with a balancer, the oil cooler and the oil filter being adjacent in a front view of the vehicle and arranged abreast in parallel with a crankshaft.

Abstract: An accessories arrangement structure for an internal combustion engine for securing a banking angle, increasing a degree of the freedom of the layout, concentrating heavy accessories and an overhanging part of the internal combustion engine, enhancing the maneuverability of the vehicle and reducing the size of the engine. An accessories arrangement structure of an internal combustion engine for a motorcycle includes an oil cooler and an oil filter that are attached together with a balancer in a lower part wherein the front of a crankcase that journals a crankcase directed in a vehicular width direction, in which the oil cooler and the oil filter are attached to the front in a vehicular traveling direction of the crankcase project with a balancer, the oil cooler and the oil filter being adjacent in a front view of the vehicle and arranged abreast in parallel with a crankshaft.

Abstract: A sub-gallery for leading oil to a cylinder head side of an engine is provided in a crankcase in such a manner as to be connected to an outlet of an oil filter and in parallel with a main gallery. A lubricating device is also provided to equally feed oil to each of portions to be lubricated in the engine, including the main gallery connected to a discharge port of an oil pump via the oil filter. This lubricating device sufficiently feeds oil to even the cylinder head side of the engine while avoiding increased pressure loss of the oil.

Abstract: A cam drive gear for an engine is described where the distance between the axes of a crankshaft and an idle shaft bearing an idle gear thereon can be made smaller, thereby contributing to a reduction in the size of the engine. In addition, a valve-operating system drive gear for an engine is also described where it is possible to restrain a cam chain from chattering at its portion wrapped around a drive sprocket.

Abstract: A chain tensioner is in sliding contact with each cam chains in a pair of banks and each of cylinder heads of the pair of banks includes a tensioner lifter that abuts on a corresponding one of the two chain tensioners from a side opposite to the cam chains. Of the two tensioner lifters, a first tensioner lifter is disposed on a cylinder head of a first bank at a portion corresponding to an outside of two banks. A second tensioner lifter is disposed on a cylinder head of a second bank at a portion corresponding to an inside of the two banks. A distance between an upper end connection surface of the cylinder head of the first bank and the tensioner lifter is set to be smaller than a distance between an upper end connection surface of the cylinder head of the second bank and the other tensioner lifter.

Abstract: A cam drive gear for an engine is described where the distance between the axes of a crankshaft and an idle shaft bearing an idle gear thereon can be made smaller, thereby contributing to a reduction in the size of the engine. In addition, a valve-operating system drive gear for an engine is also described where it is possible to restrain a cam chain from chattering at its portion wrapped around a drive sprocket.

Abstract: A chain tensioner is in sliding contact with each cam chains in a pair of banks and each of cylinder heads of the pair of banks includes a tensioner lifter that abuts on a corresponding one of the two chain tensioners from a side opposite to the cam chains. Of the two tensioner lifters, a first tensioner lifter is disposed on a cylinder head of a first bank at a portion corresponding to an outside of two banks. A second tensioner lifter is disposed on a cylinder head of a second bank at a portion corresponding to an inside of the two banks. A distance between an upper end connection surface of the cylinder head of the first bank and the tensioner lifter is set to be smaller than a distance between an upper end connection surface of the cylinder head of the second bank and the other tensioner lifter.

Abstract: A sub-gallery for leading oil to a cylinder head side of an engine is provided in a crankcase in such a manner as to be connected to an outlet of an oil filter and in parallel with a main gallery. A lubricating device is also provided to equally feed oil to each of portions to be lubricated in the engine, including the main gallery connected to a discharge port of an oil pump via the oil filter. This lubricating device sufficiently feeds oil to even the cylinder head side of the engine while avoiding increased pressure loss of the oil.