Abstract: An engine exhaust emission control system in an outboard engine is provided. The exhaust emission control system has a catalyst unit mounted in an engine block exhaust gas passage in the outboard engine. The catalyst unit comprises a catalyst carrier having at least one catalyst element carried therein and a flexible porous bag having at least a portion of the catalyst therein. The catalyst unit is formed to be positioned within the engine block exhaust passage so as to extend therealong and the catalyst unit is removably inserted and detachably mounted in the exhaust gas passage.

Abstract: An exhaust gas emission control system for a 4-cycle outboard engine is disclosed. The engine comprises a mounting member; an engine block mounted on the mounting member; an extension housing coupled to the mounting member and extending downward therefrom; and an engine oil pan mounted under the mounting member within the extension housing. The oil pan has a recess formed therein in the lengthwise direction. An exhaust gas expansion chamber is formed in the extension housing for receiving exhaust gas from the exhaust manifold of the engine. The engine exhaust emission control system comprises a catalyst assembly positioned in the exhaust gas expansion chamber, the catalyst assembly having a catalyst case aligned with the oil pan in the lengthwise direction thereof. At least a portion of the catalyst case is disposed in the recess in the oil pan.

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 multi-cylinder engine structure includes a multi-cylinder engine body having a plurality of cylinders vertically arranged therein. A fuel feed system has a fuel pump connected to a plurality of carburetors disposed in a vertical arrangement sideways of the engine body in independent correspondence to the cylinders. The fuel pump is disposed below a lowermost one of the plurality of carburetors arranged vertically. An outboard engine includes a case tiltably mounted at a stern. A multi-cylinder engine body is contained in the case. A fuel feed system supplies a fuel to a plurality of carburetors disposed in correspondence with the cylinders. A fuel filter is also provided. The fuel pump is disposed below a lowermost one of the plurality of carburetors arranged vertically and above the fuel filter in a tilted-down state of the case.

Abstract: In an outboard motor, an exhaust pipe coupled to a lower surface of a cylinder head of an engine extends downwardly through an oil case. An exhaust port, defined at a lower end of the exhaust pipe, is opened downwardly into an extension case. An exhaust gas sampling pipe, threadedly inserted into a seat surface formed on a lower surface of the extension case, extends upwardly into the exhaust pipe and has its inner end inserted into the exhaust port in the exhaust pipe. An outer end of the exhaust gas sampling pipe, extending out of the extension case, is closed by a detachable cap. Thus, it is easy to mount the exhaust gas sampling pipe for sampling an exhaust gas from the exhaust pipe for the outboard motor.

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.

Abstract: A multi-cylinder engine structure includes a multi-cylinder engine body having a plurality of cylinders vertically arranged therein. A fuel feed system has a fuel pump connected to a plurality of carburetors disposed in a vertical arrangement sideways of the engine body in independent correspondence to the cylinders. The fuel pump is disposed below a lowermost one of the plurality of carburetors arranged vertically. An outboard engine including a case tiltably mounted at a stern. A multi-cylinder engine body is contained in the case. A fuel feed system supplies a fuel to a plurality of carburetors disposed in correspondence to the cylinders. A fuel filter is also provided. The fuel pump is disposed below a lowermost one of the plurality of carburetors arranged vertically and above the fuel filter in a tilted-down state of the case.