Abstract: In a cylinder head lubricating structure for an engine, in which a breather passage which guides, toward a cylinder head, gas including oil mist generated in a crank chamber by oil splashing means housed in the crank chamber so as to splash-oil in accordance with rotation of a crankshaft is formed in a crankcase, a cylinder block and the cylinder head to supply, toward the cylinder head, lubricating oil through the breather passage, a breather chamber with which an end portion, on the crank chamber side, of the breather passage communicates is formed in the crankcase, and a one-way valve preventing backflow of the oil toward the crank chamber is attached to the crankcase to be located between the crank chamber and the breather chamber. Accordingly, it is possible to supply a sufficient amount of oil to the cylinder head side even when the head difference between the crank chamber and the cylinder head is large.

Abstract: A cylinder head apparatus for an internal combustion engine has a plurality of combustion chambers with each cylinder head having a plurality of combustion faces for fitting over the plurality of combustion chambers. The cylinder head has an elongated slot between two combustion chamber faces and has an elongated cylinder head insert having a generally T-shaped cross-section press fitted into the cylinder head slot to form a cylinder head having reduced high temperature deformations between cylinder head combustion chamber faces.

Abstract: An engine comprises a cylinder head at least partially defining a dry valley and a cover secured to the cylinder head. The cover defines a first aperture. A boss extends from the cylinder head toward the cover. The boss defines a second aperture. A fastener extends through the first aperture and at least partially through the second aperture to secure the cover to the cylinder head. The fastener defines a passage to fluidly connect the dry valley to an exterior of the engine.

Abstract: An internal combustion engine, which includes a cylinder block, a cylinder head fastened to the cylinder block, an aperture formed in a side of the cylinder head, and a conduit assembly, such as an intake runner assembly or an exhaust conduit assembly. A combustion chamber is formed by the cylinder block and the cylinder head. The intake runner assembly is received within the aperture and configured to communicate air to the combustion chamber. The intake runner assembly includes a first piece and a second piece. The first piece has a first channel that includes a bend. The second piece has a second channel that includes another bend mirroring the bend of the first channel. The first piece is coupled to the second piece such that the first and second channels together form a flow path through the intake runner assembly, and the bends of the first and second channels together form a smooth turn in the flow path.

Abstract: With regard to a surface hardening method wherein a surface of an engine member is coated with an alloy layer having high abrasive resistance so as to improve the life of the member and a production method of a piston or the like wherein abrasive resistance of the member is improved by the hardening method, a surface of a metal base material is coated uniformly with a mixture including metal powder, a binder and a solvent so as to form a coat, and the coat is dried and applied thereon with a laser or electron beam so as to be sintered and dispersed for forming an alloy layer on a surface of the metal base material and for bonding the alloy layer to the metal base material.

Abstract: A cylinder head for an internal combustion engine has at least two cylinders, each cylinder having an outlet opening for discharging the exhaust gases out of the cylinder, an assembly end side for connection to a cylinder block of the engine, an exhaust-gas line adjoining each outlet opening, the exhaust-gas lines of the at least two cylinders merging within the cylinder head to form a combined exhaust-gas line, and a coolant jacket interior to and at least partially integrated in the cylinder head, the coolant jacket made up of a lower coolant jacket and an upper coolant jacket, and at least one connection between the lower coolant jacket and the upper coolant jacket immediately adjacent the combined exhaust-gas line for allowing the passage of coolant.

Abstract: A cylinder head assembly has a substantially spherical body defining a central axis of rotation normal to the cylinder central axis and comprising a passageway there through to bring the combustion chamber into intermittent fluid communication with an exhaust duct for evacuating the burnt gases, said passageway comprising a 90 deg bend with: a first opening (31) to the exhaust duct substantially parallel to, preferably coaxial with the valve central axis of rotation, and a second opening to the combustion chamber, such that by rotation of the valve round its axis of rotation, said second opening can be intermittently brought into fluid communication with the combustion chamber.

Abstract: A cylinder head cover, a system, and a method are disclosed for sealing a cylinder head and isolating cylinder head vibrations from a cylinder head cover body. An example cylinder head cover may include a bottom carrier having a first end configured to be disposed in sealing engagement with a cylinder head. The bottom carrier may also have a second end. A cover body may be configured to provide a covering surface, and may have a side wall extending toward the cylinder head. A resilient joining element may connect the bottom carrier second end to an edge of the cover body side wall in sealing engagement.

Abstract: A motorcycle includes an engine configured to expel an exhaust from combustion chambers of cylinders in a cylinder head through exhaust ports. Each of the cylinders is provided with a recessed portion provided in an exhaust passage wall surface in a central portion of an exhaust passage of a corresponding exhaust port. This makes it possible to maintain flow rate and flow velocity of the exhaust gas, and to decrease exhaust loss. As a result, it is possible to increase engine torque by use of a simple structure. In addition, no restriction is imposed on the layout of parts around the engine, because the recessed portions are provided in the exhaust ports.

Abstract: An unfinished cylinder head casting for producing a cylinder head for internal combustion engines powered with diesel fuel includes a sealing surface, intended for mounting in a finished state on a corresponding sealing surface of an engine block, and designed on a sealing surface section of the unfinished cylinder head casting. A thickness of the sealing surface section in a casting state exhibits a machining allowance in relation to its set thickness, obtained after a material-removing finishing of the sealing surface. The sealing surface includes a combustion chamber region, associated with a combustion chamber formed in the engine block. In the case of such a cylinder head, an optimum load-bearing capacity is achieved in a simple manner in that a combustion chamber region sealing surface section machining allowance amounts to a maximum of 15% of the machining allowance of the sealing surface section in the remaining region of the sealing surface.

Abstract: A method for coating at least one exhaust port of a cylinder arranged inside a cylinder head of a combustion engine is provided, wherein the exhaust port connects the cylinder to an exhaust system. One or more surface portions of the cylinder head defining the at least one exhaust port are at least partially coated by spraying material from both the cylinder side and the exhaust system side. An apparatus for performing the method is also provided.

Abstract: A process for remanufacturing a cylinder head that includes a worn or damaged rocker arm stand adapted to receive a rocker shaft to which at least one rocker arm is mounted, the steps including machining a channel in a surface of the worn or damaged rocker arm stand, securing an insert into the channel, and machining the insert to form a remanufactured inner facing surface. The remanufactured cylinder head includes at least one rocker arm stand that has a machined channel with a remanufactured insert secured therein, the rocker shaft being disposed adjacent the inner facing surface, not the rocker arm stand.

Abstract: A cylinder head cover for a reciprocating compressor cylinder. The cover includes a first plate having a first and second channel in a surface of the first plate. The first and second channels merge within the plate at a first opening through the bottom surface of the first plate. A second plate has a pair of bores each aligned with one of the first and second channels in the first plate. A fourth plate is fastened over the second plate forming a cavity between the second and fourth plates. The fourth plate has a pair of spaced bores aligned with the bores through the second plate. A rotating third plate is disposed between the second and fourth plates. This third plate has a pair of spaced bores for sequentially aligning with one of the pair of bores through the second plate.

Abstract: A valve cover housing for internal combustion engines. In one embodiment, the valve cover housing includes a conduit for passing a coolant fluid near the valvetrain, and in another embodiment, the housing includes an internal protuberance or other structure that promotes the dripping of oil or another lubricant onto a selected region or component of the valvetrain, such as the valve springs.

Abstract: An engine assembly may include an engine structure, a first valve and a second valve. The engine structure may define a combustion chamber and first and second exhaust ports in communication with the combustion chamber. The first valve may be arranged within the first exhaust port and have a first surface area. The second valve may be arranged within the second exhaust port and have a second surface area greater than the first surface area.

Abstract: An engine assembly may include an engine structure, exhaust valves supported by the engine structure and a camshaft supported by the engine structure and engaged with the exhaust valves. The engine structure may define first, second, third and fourth combustion chambers arranged in series and a plurality of exhaust ports, each in communication with a corresponding combustion chamber. The engine structure may also define a flange region defining a first exhaust gas outlet axially aligned with the second combustion chamber and a second exhaust gas outlet axially aligned with the third combustion chamber. The engine structure may define first and second exhaust passages that extend from the first and second exhaust ports, respectively, to the first exhaust gas outlet and third and fourth exhaust passages that extend from the third and fourth exhaust ports, respectively, to the second exhaust gas outlet.

Abstract: The invention relates to a cylinder head (1) for a liquid-cooled internal combustion engine with several cylinders, comprising at least one intake port (5) and at least two exhaust ports (4) per cylinder (1), at least one first cooling chamber (2) adjacent to a fire deck and at least one second cooling chamber (3) adjacent to the first cooling chamber (2), with the second cooling chamber (3) extending over several cylinders. In order to improve cooling in the areas subjected to great thermal stress it is provided that at least one first cooling chamber (2) is provided per cylinder and the first cooling chambers (2) of two adjacent cylinders are separated from one another, with each first cooling chamber (2) comprising at least one first opening (7) and at least one transfer opening (8) to the second cooling chamber (3), and the first cooling chamber (2) is flowed through between the first opening (7) and the transfer opening (8) substantially in the longitudinal direction of the cylinder head (1).

Abstract: An exhaust insert for use with an internal combustion engine transfers heat from exhaust gases to a liquid-cooled exhaust manifold. One end of the exhaust insert extends into the exhaust port of a cylinder head, and the other end of the exhaust insert extends into an exhaust manifold. Exhaust gases are received from the cylinder head by the exhaust manifold through the exhaust insert. The exhaust insert is in contact with a surface of the exhaust manifold so as to transfer heat from the exhaust gases away from the cylinder head to the exhaust manifold.

Abstract: A cylinder block is provided with a cylinder bore and a thermally sprayed metallic coating disposed on an internal wall of the cylinder bore. The internal wall has first and second wall sections that are located at different axial locations along the internal wall of the cylinder bore. The thermally sprayed metallic coating is disposed on the internal wall of the cylinder bore by spraying droplets of a molten metal. The thermally sprayed metallic coating includes a first thermally sprayed coating portion having a first iron oxide concentration and a second thermally sprayed coating portion having a second iron oxide concentration. The first thermally sprayed coating portion is disposed on the first wall section. The second thermally sprayed coating portion is disposed on the second wall section. The second iron oxide concentration is different from the first iron oxide concentration.

Abstract: An internal combustion engine of a motor vehicle may include a cylinder head having an open cylinder head interior on a cylinder head side. A cylinder head cover may be disposed on the cylinder head for covering the cylinder head interior at the open cylinder head side. An internal wiring may be disposed in the cylinder head interior for supplying electrical energy to electrical components. The internal wiring may have at least one electrical internal interface disposed on the cylinder head in the cylinder head interior. At least one connecting bridge may have an inner connecting interface configured in a complementary manner to the internal interface, and an outer connecting interface connected electrically therewith. The external wiring may be disposed outside the cylinder head interior.

Abstract: A valve and cylinder head assembly, configured to fit a bank of cylinders of an internal combustion engine, can include a first exhaust valve for each corresponding cylinder of the bank of cylinders; a second exhaust valve for each corresponding cylinder of the bank of cylinders; a first exhaust port for each corresponding cylinder of the bank of cylinders, the first exhaust port configured to direct flow of exhaust to a first manifold in fluid communication with a first turbocharger; and a second exhaust port for each corresponding cylinder of the bank of cylinders, the second exhaust port configured to direct flow of exhaust to a second manifold in fluid communication with a second turbocharger; where the shape of the first exhaust ports differs from the shape of the second exhaust ports; where each of the first exhaust valves controls flow of exhaust to a respective one of the first exhaust ports; and where each of the second exhaust valves controls flow of exhaust to a respective one of the second exhaust

Abstract: A cylinder head modification method includes the steps of selecting a cylinder head for an internal combustion engine having a plurality of combustion chambers and the cylinder head having a plurality of combustion chamber faces on the top of each combustion chamber. An elongated cylinder head insert is selected having a generally T-shaped cross-section and then forming an elongated slot in the selected cylinder head between a pair of combustion chamber faces. The elongated slot is shaped to receive the elongated cylinder head insert therein. A method includes press fitting the elongated cylinder head insert into the elongated slot and the cylinder head to thereby reduce localized high temperature deformations in the cylinder head. The method includes the step of heating the cylinder head to expand the slot for pressure fitting the cylinder head insert thereinto.

Abstract: A cylinder head adapted to be mounted to a cylinder block of an internal combustion engine has a cooling jacket at least partially integrated in the cylinder head. The engine has two groups of cylinders: inside cylinders and outside cylinders. Each cylinder has at least one exhaust port, each leading to an individual duct. Individual ducts of outside cylinders converge to form an outside combined duct. In a four-cylinder, individual ducts of inside cylinders converge to form an inside combined duct with the inside combined duct remaining separated from the outside combined duct by the cooling jacket. The inside combined duct is farther away from the mounting surface of the cylinder head to the cylinder block than the outside combined duct. The cooling jacket includes: upper, middle, and lower cooling jackets and connectors between the upper and lower cooling jackets.

Abstract: A camshaft cover mounts to a cylinder head and defines cavities for oil control valves that adjust the position of camshafts via camshaft phaser assemblies. The cavities are positioned above the camshafts when the camshaft cover is mounted to the cylinder head. A feed passage communicates pressurized fluid from the cylinder head to the cavities when the camshaft cover is mounted to the cylinder head. Control passages communicate fluid from the cavities to the camshaft phaser assemblies when the camshaft cover is mounted to the cylinder head.

Abstract: A cylinder head for an internal combustion engine incorporates—in a single cast piece—the engine exhaust manifold. A lower cooling jacket and an upper cooling jacket arranged below and above said integrated exhaust manifold are provided in the body of the head. At least one of such cooling jackets is divided into separate transverse chambers by partitions extending transverse with respect to the longitudinal direction of the head, so that the cooling fluid is forced to traverse such transverse chambers parallel according to the direction orthogonal to the longitudinal direction of the head.

Abstract: A central direct injection (DI) cylinder head is configured with an intake valvetrain and an exhaust valvetrain separated by an uncovered central DI valley. The uncovered central DI valley limits oil flow from the high side chamber to the low side chamber and PCV transfer. Oil drainage and additional PCV transfer between the intake and exhaust chambers is provided by drain/vent passages integrally cast into the casting of the cylinder head. The drain/vent passages may be of varying configuration, and may be located between an injector port of a first cylinder set and a spark plug port of an adjacent cylinder set, or at either or both ends of the cylinder head. A method is provided to form a casting of the cylinder head as described herein, including casting of a plurality of drain/vent passages between the first chamber and the second chamber of the cylinder head.

Abstract: An exemplary embodiment includes a valve cover for automotive engines with convenient holes for adjusting the valves without removing the valve cover from the engine. Rubber plugs close the holes in the valve cover.

Abstract: An induction system for an internal combustion engine includes an upper intake for receiving air from a supply, such as a turbocharger, and a lower intake which combines a cylinder valve actuator cover, a plenum for receiving air from the upper intake, and a number of intake runners which extend across, an integrally with, the cylinder valve actuator cover to cylinder head intake ports which are configured at outboard sides of the engine cylinder head.

Abstract: A spark plug and cylinder head assembly includes a spark plug and a cylinder head of an engine. The cylinder head has a bore and a surface which faces a combustion chamber of the engine and on which the bore opens. The spark plug is fit in the bore of the cylinder head, and includes a metal shell, an insulator retained in the metal shell, a center electrode secured in the insulator, and a ground electrode facing the center electrode through a spark gap. An end surface of the metal shell has an outer edge and an inner edge, and tapers from the outer edge to the inner edge in a direction toward the inside of an air pocket formed between the metal shell and the insulator. The outer edge of the end surface of the metal shell protrudes from the surface of the cylinder head into the combustion chamber.

Abstract: An engine includes exhaust manifold integrally formed with a cylinder head. The engine may include an exhaust manifold having at least one single exhaust outlet for exhausting exhaust gas that is exhausted from at least two cylinders that are not adjacent with each other, wherein periods during which exhaust valves are open are not overlapped with each other between the at least two cylinders. The exhaust manifold is integrally formed with the cylinder head such that costs can be reduced. Also, the water jacket is formed between the exhaust passages of the exhaust manifold such that the durability of the turbocharger that is affected by a heat load can be improved. Also, the twin scroll turbocharger is directly connected to the exhaust outlet of the manifold such that the compression ratio of the intake air can be effectively improved.

Abstract: An engine assembly may include an engine block, a cylinder head, and a valvetrain assembly. The cylinder head may be fixed to the engine block. The valvetrain assembly may include a valve actuating member, a support member, and a first fastener engaged with the support member and the engine block that fixes the support member to the engine block. The valve actuating member may be rotatably supported on the support member.

Abstract: A cylinder head having a coolant passage therein includes a coolant inlet, an exhaust valve seat portion, intake valve seat portion, and a spark plug mounting portion formed centrally in the cylinder head, wherein a guide rib is formed close to the coolant inlet for coolant to flow near the spark plug mounting portion along the exhaust valve seat portion and a coolant outlet is disposed near to a corner of the intake valve seat portion.

Abstract: An internal combustion engine for a vehicle, such as a motorcycle, includes a crankcase, two banks of cylinders projecting from the crankcase in a 56-57 degree V-configuration, a plurality of pushrods, and a plurality of camshafts supported by the crankcase. The two banks of cylinders include a first cylinder bank that projects from the crankcase to a first cylinder head, and a second cylinder bank that projects from the crankcase to a second cylinder head. The plurality of intake and exhaust valve pushrods extend between the crankcase and the first and second cylinder heads, driven by one intake camshaft and two exhaust camshafts.

Abstract: A cylinder head of an internal combustion engine comprises a camshaft that is mounted in the axial direction via at least one rolling bearing, wherein the at least one rolling bearing may be formed such that all occurring axial forces may be absorbed via the at least one rolling bearing.

Abstract: A cylinder head having a plurality of integrally formed port-exhaust manifold assemblies therein, wherein the port-exhaust manifold assembly is integrally formed in the cylinder head by extending a plurality of exhaust port of an engine to function as an exhaust manifold and the plurality of the port-exhaust manifold assemblies is arranged in a triangle when each center portion of outlet portions thereof are connected.

Abstract: In a multi-cylinder internal combustion engine, a hydraulic valve rest mechanism is mounted on a valve operating device, which performs open-close driving of an engine valve which is arranged in a cylinder head of an engine body having a plurality of cylinders in an openable-and-closable manner. The hydraulic valve rest mechanism is operated with an oil pressure that is controlled by a hydraulic control device so as to close and rest engine valves of a plurality of cylinders for bringing the cylinders into a rest state Therefore, the miniaturization of the multi-cylinder internal combustion engine along an axis of a crankshaft and can shorten a length of an oil passage which connects a hydraulic valve rest mechanism and a hydraulic control device. A hydraulic control device is arranged on an engine body directly above a portion thereof corresponding to a cylinder that is expected to assume a cylinder rest state.

Abstract: A cylinder head of an internal combustion engine is fitted with rocker arms. Camshafts are disposed so that the rocker arms and cams will be brought into contact with each other. The camshafts are rotatably supported by lower bearings, which supports the camshafts from below, and by upper bearings integrated with a head cover. The head cover is provided with visual observation windows that make it possible to see valve system parts through the head cover. A visual observation window covers for covering the visual observation windows are fixed to the head cover.

Abstract: A cam cap has a wall portion that extends between two cam cap portions integrally formed and having connection portions respectively, and therefore the rigidity of the cam cap is high and thus the relative positional accuracies of oil passage connection faces of the connection portions are high even after the cam cap is mounted on an internal combustion engine.

Abstract: A cylinder head has a cylinder head body, a camshaft housing mounted on the cylinder head body, and cam caps mounted on the camshaft housing. The camshaft housing has through holes into which bolts are inserted to secure the camshaft housing and the cam caps together to the cylinder head body when assembling the engine. Internal threads are formed on the inner surfaces of the through hole, respectively. When rounding the cam holes before assembling the engine, second bolts are temporarily tightened to the internal threads of the through holes to secure the cam caps to the cam housing.

Abstract: An engine assembly may include a cylinder head and a fluid control assembly. The cylinder head may include first and second walls opposite one another and extending from a base region defining a cavity. The cylinder head may define a first oil passage extending through an interior surface defining the cavity. The fluid control assembly may include a first oil control valve and a first conduit. The first oil control valve may be fixed to the base region and may define a first port in fluid communication with the first oil passage and a second port in fluid communication with a second oil passage in the cylinder head. The first conduit may extend from the first oil control valve toward the first wall and may provide the fluid communication between the first port of the oil control valve and the first oil passage in the cylinder head.

Abstract: A fluid flow valve in a cylinder head comprises a first valve end and an axially disposed second shaft end connected by a valve shaft. A first valve member is located at the first valve end and a second valve member is located axially from, and in fixed relationship to, the first valve member along the valve shaft. A valve support extends axially between and connects the first valve member and the second valve member; the valve support including an axially extending wall portion having circumferentially spaced support struts extending radially between the valve shaft and the wall portion. Fluid flow passages extend axially through the wall portion, between the circumferentially spaced support struts, wherein fluid flows simultaneously about the exterior of the wall portion and through the fluid flow passages in the wall portion when the valve member is biased to an open position.

Abstract: In one example, a valve seat insert for a cylinder head seat pocket of an internal combustion engine is described. The valve seat insert comprises an annular body comprising a first material and including an inner surface, an outer surface opposite the inner surface, a front surface adjoining the inner and outer surfaces, and a back surface opposite the front surface adjoining the inner and outer surfaces. The front surface includes an inner circumference greater than an inner circumference of the back surface. The back surface includes a first recession inlaid with a sacrificial anode comprising a second material different from the first material and having an exposed surface. In this manner, it may be possible to substantially prevent corrosion of the cylinder head seat pocket. Further, various approaches for reducing corrosion of the cylinder head seat pocket are described.

Abstract: The invention relates to a cylinder head (1) of an at least one-cylinder internal combustion engine with direction injection of a motor vehicle with a flame deck (2) and with an oil deck (3). An intermediate deck (4) is situated between the flame deck (2) and the oil deck (3), and at least one injector pipe (5) extends from the flame deck (2) up to the oil deck (3). The intermediate deck (4) joins a lower area of an injector pipe (5), particularly an injector dome (6) that is situated approximately centrally in the area of the flame deck (2). When viewing from the flame deck (2), the intermediate deck (4) extends outward in a concave-like manner so that the intermediate deck (4) joins a lateral wall (7) in a range of 40% to 60% of the distance between the flame deck (2) and the oil deck (3).

Abstract: A method to produce cast iron articles with various graphite morphologies is disclosed that provides cast iron with tailored properties at different locations of the article. Flake graphite morphology is preferably created at locations requiring excellent thermal conductivity or lubricity. Spheroidal graphite morphology is preferably created at locations requiring excellent strength or mechanical fatigue life. These methods may be particularly valuable for the production of heavy duty diesel engine components.

Abstract: An oil supply structure of a continuously variable valve timing apparatus includes: a first oil filter to receive and filter oil from a main gallery; a first oil control valve to receive oil from the first oil filter; a first continuously variable valve timing apparatus to receive oil from the first oil control valve; a second oil filter to receive and filter oil from the main gallery; a second oil control valve to receive oil from the second oil filter; a second continuously variable valve timing apparatus to receive oil from the second oil control valve; and an oil supply line in a cylinder head, that fluidly connects the main gallery, the oil filters, the oil control valves, and the continuously variable valve timing apparatuses. The cylinder head includes the oil supply line, and various holes for the components of the oil supply structure to be disposed therein.

Abstract: An insulative piston or piston cap creates a highly thermally resistive path in the axial direction of the piston or piston cap toward a crank case of an engine. An insulative cylinder is configured to be positioned around the insulative piston and adjacent an insulative cylinder head, and to provide thermal resistance in the cylinder's axial direction. The insulated cylinder head is configured to resist heat flow in the axial direction away from the crank case. High temperature insulation surrounding these structures is configured to resist heat flow out of a combustion chamber of the engine. These insulative components, together, form the fully insulated combustion chamber.

Abstract: An internal combustion engine cylinder head is based upon a one-piece structure including a number of exhaust runners, an exhaust collector, and a turbocharger exhaust turbine housing, all formed as one-piece.

Abstract: A modular engine family comprises an engine block assembly having an upper end extending at an angle ? from a rear of the engine block assembly to a front thereof. An engine block closes the upper end and defines a crankcase comprising a crankshaft having three journals supported by journal bearings for rotation therein. First and second piston pins and associated first and second piston/rod assemblies are disposed in piston cylinders of a first cylinder housing assembly wherein the first and second piston pins are located in the same radial position on the crankshaft and are spaced longitudinally to define a firing interval of 360 degrees. A cylinder head is configured to close open ends of the piston cylinders to thereby define combustion chambers with the first and second pistons; the cylinder housing assembly reclined from vertical towards the rear of the engine block by an angle ?.

Abstract: An air-cooled engine (10) is cooled by cooling air (Wi). The air-cooled engine (10) includes a cylinder block (33) and a cylinder head (28). The cylinder block (33) has cylinder cooling through-ducts (101, 102) capable of transmitting cooling air (Wi), on the periphery of a cylinder (26). The cylinder head (28) has a head-cooling through-duct (104) capable of transmitting cooling air (Wi). The cylinder-cooling ducts (101, 102) and the head-cooling duct (104) extend in a direction perpendicular to the axial line (109) of the cylinder (26), and are communicated with each other by means of communication channels (105, 105).

Abstract: In an internal combustion engine, one end of a cylinder head (1) in a longitudinal direction is provided with a cooling water inflow port (19) leading to the inside of the cylinder head (1), while the other end of the cylinder head (1) in the longitudinal direction is provided with an outflow port (20) of main cooling water flow (X) flowing through the center inside the cylinder head (1). Further, an outflow port (21) of sub cooling water flows (Y) branched from the main cooling water flow (X) and flowing around the merged part of the exhaust port (5) is provided. An adapter (23) communicated with the main cooling water outlet (20) and sub cooling water outlet (21) and combining these outflow ports (20, 21) into a single cooling water outlet (22) is fixed to the outer wall surface of the cylinder head (1).