Abstract: An outboard motor body case supported on a swivel shaft through a connecting member. The swivel shaft is vertically swingable about a tilting shaft. An engine is mounted at an upper portion of the outboard motor body case, with a crankshaft thereof being oriented vertically, and a flywheel is mounted at a lower end of the crankshaft and disposed between an engine block and the connecting member. A dynamo is mounted within the flywheel, and a starter motor is engaged with a ring gear which is formed around an outer periphery of the flywheel. Thus, since the flywheel having a large weight is mounted at the lower end of the crankshaft, the position of the center of gravity of the outboard motor is lowered. Therefore, it is possible to easily perform a tilting-up about the tilting shaft with a small force. Moreover, since the flywheel is mounted on a power taking-off side of the crankshaft, the torsional vibration of the crankshaft can be reduced.

Abstract: An outboard motor body case supported on a swivel shaft through a connecting member. The swivel shaft is vertically swingable about a tilting shaft. An engine is mounted at an upper portion of the outboard motor body case, with a crankshaft thereof being oriented vertically, and a flywheel is mounted at a lower end of the crankshaft and disposed between an engine block and the connecting member. A dynamo is mounted within the flywheel, and a starter motor is engaged with a ring gear which is formed around an outer periphery of the flywheel. Thus, since the flywheel having a large weight is mounted at the lower end of the crankshaft, the position of the center of gravity of the outboard motor is lowered. Therefore, it is possible to easily perform a tilting-up about the tilting shaft with a small force. Moreover, since the flywheel is mounted on a power taking-off side of the crankshaft, the torsional vibration of the crankshaft can be reduced.

Abstract: An outboard motor body case supported on a swivel shaft through a connecting member. The swivel shaft is vertically swingable about a tilting shaft. An engine is mounted at an upper portion of the outboard motor body case, with a crankshaft thereof being oriented vertically, and a flywheel is mounted at a lower end of the crankshaft and disposed between an engine block and the connecting member. A dynamo is mounted within the flywheel, and a starter motor is engaged with a ring gear which is formed around an outer periphery of the flywheel. Thus, since the flywheel having a large weight is mounted at the lower end of the crankshaft, the position of the center of gravity of the outboard motor is lowered. Therefore, it is possible to easily perform a tilting-up about the tilting shaft with a small force. Moreover, since the flywheel is mounted on a power taking-off side of the crankshaft, the torsional vibration of the crankshaft can be reduced.

Abstract: A V-shaped multi-cylinder engine is mounted in such a manner that a crankshaft is mounted in a vertical attitude and cylinders are opened into a V-shape in a rearward direction. An intake silencer is mounted above a throttle body which is disposed in front of a crankcase portion of the engine. The intake silencer includes an intake silencing chamber defined by a belt cover which covers a belt of a valve operating mechanism and by a lower wall member. Two left and right air intake pipes extend downwardly from the intake silencing chamber and open into an engine compartment. A single intake-air introducing pipe extends downwardly from the intake silencing chamber and is connected to an upper end of the throttle body. Thus, it is possible to reduce the intake noise of the engine for an outboard engine system.

Abstract: An exhaust pipe for guiding an exhaust gas from an engine into an exhaust gas expansion chamber defined within an extension case is connected to a protrusion of an oil pan which is mounted on a lower surface of a mount case that supports the engine at its upper portion. A breathing bore is formed in an upper portion of the exhaust pipe, and an outer side of the breathing bore is covered with a shield plate. Therefore, water cannot enter the exhaust pipe through the breathing bore. A cooling-water supply pipe for introducing cooling water from a cooling-water pump into the engine is formed with a cooling-water ejection bore which is located at a position in which it is not opposed to the breathing bore. Therefore, even if cooling water is ejected through the cooling-water ejection bore to the exhaust pipe to cool the latter, the cooling water cannot enter the exhaust pipe.

Abstract: An upper intake pipe and a lower intake pipe interconnecting a left bank and a throttle body are disposed along a left side of a V-shaped multi-cylinder engine having a vertically placed crankshaft. The lower intake pipe is disposed by utilizing a waste space which is defined between a starter motor and an oil filter, while the oil filter is disposed by utilizing a waste space which is defined between the upper and lower intake pipes. Thus, it is possible to rationally dispose the intake pipes and other auxiliaries on a side of an engine block to reduce the size of the engine for the outboard engine system.

Abstract: An exhaust pipe extending from an engine of an outboard motor is covered with an exhaust pipe cover that defines a cooling water passage around an outer periphery of the pipe. An exhaust gas sampling pipe has a base end inserted into the exhaust pipe through the exhaust pipe cover, and a tip end occluded by a detachable plug. The exhaust gas sampling pipe and the plug are accommodated within an engine cover detachably mounted on an upper portion of an undercase, whereby it is protected against rusting due to the deposition of seawater and damaging due to collision against another object.

Abstract: A plurality of cylinders are defined in a single cylinder block, and a single cylinder head common to the cylinders is mounted on the cylinder block. Exhaust passages are provided in the cylinder head at a location corresponding to an inner side and central portion of a V-shape formed by the cylinders, the exhaust passages communicating with the cylinders, respectively. Intake passages are provided in the cylinder head at a location corresponding to opposite outside positions of the V-shape, the intake passages communicating with the cylinders, respectively. The intake passages open into a side of the cylinder head on opposite sides of the V-shape, and fuel injection nozzles provided in the intake passages, respectively. The exhaust passage extend parallel to a crankshaft within the cylinder head and open into the corresponding side of the cylinder head. A water jacket is defined around the exhaust passages to surround the exhaust passages.

Abstract: An outboard engine structure is provided including an engine mounted in an upper portion of the structure, wherein an exhaust gas from the engine is passed through an exhaust passage located vertically within an engine body case, into a lower portion of the case and discharged into water. A catalytic converter is positioned adjacent an oil pan the said engine. The oil pan is mounted in a suspended manner in an upper area within the engine body case and the catalytic concerted is incorporated in the middle of the exhaust passage. The catalytic converter is fixed to and supported on the oil pan. Thus, it is easy to place the catalytic converter in the engine body case.

Abstract: An engine E of an outboard motor O includes a carburettor 29 at an upstream end of an intake manifold 28, and an air intake 30 is detachably fixed to the carburettor 29 by two bolts 44. A cylinder block 21 of the engine E and a coupling portion 30-2 of the air intake 30 are interconnected through blow-by gas passages 40 and 41 with an oil separating chamber 39 interposed therebetween. The coupling portion 30-2 is provided at a location offset upwardly from axes of the two bolts 44. Therefore, both of the operation of the bolts 44 for attaching and detaching the air intake 30 and the operation of attaching and detaching the blow-by gas passage 41 to and from the coupling portion 30-2 can be conducted without any hindrance.