Abstract: An outboard motor is provided with an engine compartment exhaust passage that is formed by joining via a joining part an exhaust manifold connected to a cylinder head and an exhaust guide connected to an exhaust passage of a mount case. By bending the portion of the exhaust manifold that is lower than the lowest combustion chamber so as to be farther away from the cylinder head than other portions of the exhaust manifold, the space in which the exhaust manifold is arranged can be minimized, and the joining part can be prevented from interfering with the cylinder head while minimizing any influence on the exhaust efficiency.

Abstract: An outboard motor water-cooled vertical engine is provided in which a crankshaft is disposed substantially vertically, a timing chain for transmitting a driving force of the crankshaft to a camshaft is disposed in an upper part of the cylinder block and a cylinder head, and an upper part of the timing chain is covered with a chain cover. Provided in the chain cover are thermostats for controlling the flow of cooling water in a cylinder block cooling water jacket and a cylinder head cooling water jacket. Therefore, the thermostats can be accessed from the top of the engine for maintenance without being obstructed by the timing chain, and moreover it is easy to manipulate a drain pipe for discharging cooling water from the thermostats.

Abstract: An oil pan-coupled surface 115 formed on a lower surface of an engine block 11 having a crankshaft 15 supported to be directed vertically is extended below a cylinder head 12 beyond a line L extending downwards from a cylinder head-coupled surface 114 formed on a rear surface of the engine block 11. Thus, it is possible to increase the area of the oil pan-coupled surface 115 without interference with the cylinder head-coupled surface 114 and to increase the volume of an oil pan 411 coupled to the oil pan-coupled surface 115. Moreover, the cylinder head-coupled surface 114 and the oil pan-coupled surface 115 are not continuous with each other and hence, there is no possibility that the sealing of the coupled surfaces 114 and 115 may be impeded.

Abstract: A water-cooled vertical engine includes a cylinder block cooling water jacket formed in a cylinder block and a cylinder head cooling water jacket formed in a cylinder head, the jackets being substantially independent. Cooling water from a cooling water pump is supplied to the cylinder block cooling water jacket via through holes, and cooling water branching just before the cylinder block cooling water jacket is supplied to the cylinder head cooling water jacket via a pair of cooling water passages through gasket faces of the cylinder block and the cylinder head.

Abstract: An outboard motor equipped with a water-cooled engine includes an exhaust manifold cooling water jacket for cooling an exhaust manifold for discharging to the outside exhaust gas from a combustion chamber, the exhaust manifold cooling water jacket being supplied with cooling water from a cooling water pump. A water outlet provided in the highest part of the exhaust manifold cooling water jacket is made to communicate with a water check outlet for confirming the circulation of cooling water due to operation of the cooling water pump. Thus, it is possible to reliably discharge air residing within the exhaust manifold cooling water jacket through the water check outlet. Since the water check outlet is used as an opening for discharging air, it is unnecessary to provide a special air outlet.

Abstract: In an engine, a cover member closing an opening in an engine block is integrally formed with supporting arms extending radially outwards beyond an outer periphery of a flywheel mounted on a crankshaft supported at its one end on the cover member, and a recoil starter located axially outside the flywheel is supported on the supporting arms. Thus, the recoils starter can be supported easily and reliably without provision of a special mounting bracket and a stay and while preventing the interference with the flywheel. Moreover, the coaxiality of the recoil starter and the crankshaft can be ensured.

Abstract: An outboard engine system includes a case member which is disposed below an engine body and integrally provided with an oil pan opening upwards, and a passage wall extending vertically to define an exhaust gas passage through which an exhaust gas flows. A portion of an outer wall of the case member is formed by the passage wall, and a recess is provided in the outer wall of the case member with a portion of the passage wall facing the recess. The recess is covered with a plate member fixed to the outer wall of the case member, and a cooling water passage, through which cooling water flows, is defined between the plate member and the recess. Thus, the passage wall integral with the oil pan is cooled effectively, while avoiding increases in size and weight.

Abstract: A structure for fitting a generator stator to an engine is provided which allows generator stators having different shapes to be fitted selectively to a common engine main body. In order to selectively fit a first or second generator stator having different shapes from each other to the outside wall of an engine main body, a plurality of first fitting bosses for bolting the first generator stator and a plurality of second fitting bosses for bolting the second generator stator are provided at different positions on the outside wall.

Abstract: An outboard engine system includes a casing having a driving-force transmitting device provided therein, and an engine for transmitting power through the driving-force transmitting device to a propeller. The casing and the engine are carried on a hull for tilting-up movement. An engine cover made of a synthetic resin covers at least an upper portion of the engine, and an undercover comprises a pair of cover halves made of a synthetic resin and connected to each other to cover at least a lower portion of the engine from opposite sides. The undercover is detachably connected at its upper end to a lower end of the engine cover and fixed to an upper portion of the casing. In such outboard engine system, the undercover is detachably fixed at its upper portion to a body of the engine. Thus, the undercover can be supported so as to give an impression that the engine cover and the undercover are rigid during a tilting-up operation.

Abstract: In a gas-liquid separation device for an internal combustion engine used in an outboard motor, comprising: a gas-liquid separation chamber defined in a part of the engine, the chamber being provided with first and second ports communicating with a crankcase, and a third port communicating with an intake passage, the first port is provided with a first one-way valve for allowing blow-by gas from the crankcase to flow into the chamber, and the second port is provided with a second one-way valve for allowing oil separated from the blow-by gas to be discharged from the chamber, wherein the second one-way valve includes a reed valve member adapted to selectively close the second port, and a valve seat defined by an annular surface which is elevated from a surface of a wall surrounding the second port and defines a larger opening area than the second port.

Abstract: An outboard engine system includes a 4-cycle engine. The engine includes an engine block, a cylinder head coupled to the engine block and having an intake port in one side thereof, a carburetor including a carburetor body disposed on one side of the engine block adjacent the intake port and having an intake passageway, and a bypass-type starting device mounted to the carburetor body, and an intake pipe means which connects the intake passageway and the intake port to each other. At least an upper half of the engine including the carburetor is covered with an engine cover. In such outboard engine system, the bypass-type starting device of the carburetor is mounted to the carburetor body between the intake passageway and the engine block.

Abstract: An engine includes an engine block having a crankcase, which has a first bearing on one sidewall and an opening on the other sidewall to assemble a crankshaft. A case cover is coupled to the crankcase by a plurality of bolts to close the opening, and which has a second bearing. Two knock pins are fit into the crankcase and the case cover over their joint faces at locations closer to a cylinder bore in the engine block than the second bearing. The knock pins define the position for coupling the crankcase and the case cover to each other and contribute to an increase in rigidity of the case cover. The supporting strength for the crankshaft is increased and the weight of the case cover is reduced.

Abstract: In an outboard engine system in which a passage defining member having a passage wall defining an exhaust gas passage for guiding an exhaust gas from an engine is provided at its outer wall with a recess and a seal surface surrounding the recess; a fluid passage isolated from the exhaust gas passage is defined between the recess and a lid member which is mounted to the outer wall of the passage defining member with a seal member interposed between the lid member and the seal surface; and an exhaust gas sampling pipe is inserted into the exhaust gas passage through an insertion bore provided in the passage defining member to open into the seal surface, it is arranged that the seal member is formed to surround an opening at an outer end of the insertion bore, and the exhaust gas sampling pipe is gas-tightly fixed in the lid member to extend through the lid member. Thus, the exhaust gas sampling pipe can be inserted into the exhaust gas passage, while avoiding an increase in size of the lid member.

Abstract: In an outboard engine system in which a passage defining member having a passage wall defining an exhaust gas passage for guiding an exhaust gas from an engine is provided at its outer wall with a recess and a seal surface surrounding the recess; a fluid passage isolated from the exhaust gas passage is defined between the recess and a lid member which is mounted to the outer wall of the passage defining member with a seal member interposed between the lid member and the seal surface; and an exhaust gas sampling pipe is inserted into the exhaust gas passage through an insertion bore provided in the passage defining member to open into the seal surface, it is arranged that the seal member is formed to surround an opening at an outer end of the insertion bore, and the exhaust gas sampling pipe is gas-tightly fixed in the lid member to extend through the lid member. Thus, the exhaust gas sampling pipe can be inserted into the exhaust gas passage, while avoiding an increase in size of the lid member.

Abstract: An outboard motor has a first case member and a second case member connected to the first case member to form an enclosure having an inner space in which is mounted an engine. The first case member has an air intake hole for taking air into the inner space and a vent hole for exhausting the air after it circulates in the inner space to cool the interior of the inner space. An alternator is disposed in the inner space of the enclosure and has a hollow casing, air passage holes formed in the hollow casing, and cooling fans for drawing air from the air passage holes into the hollow casing to cool the alternator. A cover member is disposed in the inner space of the enclosure and covers at least a portion of the alternator.

Abstract: In a gas-liquid separation device for an internal combustion engine used in an outboard motor, comprising: a gas-liquid separation chamber defined in a part of the engine, the chamber being provided with first and second ports communicating with a crankcase, and a third port communicating with an intake passage, the first port is provided with a first one-way valve for allowing blow-by gas from the crankcase to flow into the chamber, and the second port is provided with a second one-way valve for allowing oil separated from the blow-by gas to be discharged from the chamber, wherein the second one-way valve includes a reed valve member adapted to selectively close the second port, and a valve seat defined by an annular surface which is elevated from a surface of a wall surrounding the second port and defines a larger opening area than the second port.

Abstract: An engine E is received vertically in an engine room 36 covered by an engine cover 4, and a generator 62 is arranged in a position above a front end of a crankcase 7 of the engine E and facing an opening 101 formed at a front of belt covers 10, 11. An air flowing from an air intake port 41 formed at a rear, upper portion of the engine cover 4, toward an intake opening 791, of an intake silencer 76 provided at a front, lower end of the engine room 36 cools the generator 62 disposed in a path of flow. A part of air in the engine room 36 is introduced into an interior of the belt covers 10, 11 through the opening 101 to be discharged outside from a ventilation port 751, and at that time the generator 62 is cooled by the air which passes through the opening 101.

Abstract: An outboard engine system includes a case member which is disposed below an engine body and integrally provided with an oil pan opening upwards, and a passage wall extending vertically to define an exhaust gas passage through which an exhaust gas flows. A portion of an outer wall of the case member is formed by the passage wall, and a recess is provided in the outer wall of the case member with a portion of the passage wall facing the recess. The recess is covered with a plate member fixed to the outer wall of the case member, and a cooling water passage, through which cooling water flows, is defined between the plate member and the recess. Thus, the passage wall integral with the oil pan is cooled effectively, while avoiding increases in size and weight.

Abstract: An engine includes an engine block having a crankcase, which has a first bearing on one sidewall and an opening on the other sidewall to assemble a crankshaft. A case cover is coupled to the crankcase by a plurality of bolts to close the opening, and which has a second bearing. Two knock pins are fit into the crankcase and the case cover over their joint faces at locations closer to a cylinder bore in the engine block than the second bearing. The knock pins define the position for coupling the crankcase and the case cover to each other and contribute to an increase in rigidity of the case cover. The supporting strength for the crankshaft is increased and the weight of the case cover is reduced.

Abstract: A structure for fitting a generator stator to an engine is provided which allows generator stators having different shapes to be fitted selectively to a common engine main body. In order to selectively fit a first or second generator stator having different shapes from each other to the outside wall of an engine main body, a plurality of first fitting bosses for bolting the first generator stator and a plurality of second fitting bosses for bolting the second generator stator are provided at different positions on the outside wall.