One embodiment of the invention relates to an internal combustion engine including an engine block having a first cylinder and a second cylinder, a crankshaft configured to rotate about a crankshaft axis, a flywheel coupled to the crankshaft, a throttle body, an air filter assembly, a first electric fan coupled to a first duct, and a second electric fan coupled to a second duct. The first duct is configured to direct cooling air directly over the first cylinder. The second duct is configured to direct cooling air directly over the second cylinder. The first cylinder is at least partially within the first duct. The second cylinder is at least partially within the second duct.

Methods and systems are provided for reducing temperature of an engine or single cylinder(s) of the engine at start/stop events where the engine is stopped from combusting air and fuel, and in response to an overheating engine condition. In one example, a method comprises activating an electric air compressor to direct cooling air flow through a first single cylinder of the engine, to reduce a temperature of the first single cylinder to a desired temperature prior to a request to restart the engine. In this way, a single cylinder indicated to be overheating may be effectively cooled, without employing methodology that would otherwise cool the engine as a whole, which may thus prevent engine degradation and which may conserve power of an onboard energy storage device.

One embodiment of the invention relates to an internal combustion engine including an engine block, a crankshaft configured to rotate about a crankshaft axis, a flywheel coupled to the crankshaft, a throttle body, an electric fan, and an air filter assembly configured to filter incoming air from an air intake and provide cleaned air to a throttle body. The engine block includes a cylinder. The throttle body is configured to throttle incoming air to the cylinder.

A utility vehicle includes: an air-cooled engine; a cooling fan disposed on one side of the engine with respect to a vehicle widthwise direction and configured to supply a cooling air towards a cylinder unit of the engine; an exhaust pipe disposed on the other side of the engine with respect to the vehicle widthwise direction and connected with an exhaust port of the cylinder unit; an oxygen sensor fitted to the exhaust pipe; and a shield configured to prevent muddy water, which is swirled by the cooling fan, from depending on the exhaust pipe.

The temperature of exhaust gas discharged from a compact air-cooled engine used as a power source for an engine-driven working machine is reduced. An engine has a muffler mounted directly to the exhaust opening of the cylinder, and a resin muffler cover covering the muffler. An exhaust gas restriction member is provided to a wall surface of the muffler, and two exhaust passages serving as outlets for exhaust gas are formed in the exhaust gas restriction member. The exhaust passages are arranged independent of each other, and the streams of discharged exhaust gas are discharged to be slightly separated from each other as the streams flow away from the exhaust openings. The separated streams of discharged exhaust gas form a negative pressure space between the streams promoting the introduction of a cooling air stream into the negative pressure portion. Thus, the temperature of the exhaust gas can be reduced.

A front fender is provided in front of an air-cooled engine which is a drive source of a motorcycle. An air introduction hole which opens frontward is formed at a front part of a cylinder head of the air-cooled engine. A space around a plug attachment portion for a spark plug and a space in front of the cylinder head communicate with each other through the air introduction hole. A guide portion for guiding incoming wind toward the air introduction hole is formed at a rear part of the front fender.

A motor engine having an oxygen sensor is provided, including: a cylinder head, including a main body and a protruding tube protruding outwardly from the main body, the main body including a first end portion, a second end, and a combustion chamber, the protruding tube having a protrusive receptacle protruding outwardly therefrom, the main body defining an axial direction; an exhaust passage, communicated with the combustion chamber and the protruding tube; an oxygen sensor, inserted into the protrusive receptacle, including a sensing portion which is inserted into the exhaust passage; wherein as viewed in a lateral direction of the cylinder head, two surfaces of the main body along the axial direction disposed on two opposite sides defines two boundary lines, the oxygen sensor and the main body are in an overlapping arrangement and does not protrude out of the two boundary lines.

A general purpose engine includes: a crankcase to support an engine rotary shaft; a cylinder unit extending from the crankcase in a direction perpendicular to an axis of the engine rotary shaft; a cooling fan fixed to one of opposite ends of the engine rotary shaft; and a fan housing configured to have an air induction opening defined therein for the cooling fan and to cover the crankcase and the cylinder unit from one side of the engine rotary shaft. At a position of the fan housing which is opposed to the cooling fin of the cylinder unit, a cleaning access window is defined. The cleaning access window is covered by a debris covering that is capable of being selectively opened and closed. The debris covering has one end portion engaged with the fan housing and the other end portion removably mounted on the fan housing by a magnetic body.

A cooling shroud assembly for an engine is disclosed. This cooling shroud assembly includes a shroud body. There is an inlet door or flap to an interior of this shroud body, along with an outlet door or flap from this shroud body. When installed on an engine that is incorporated by a moving vehicle (e.g., aircraft, unmanned aerial vehicle, radio-controlled aircraft, watercraft), airflow through the shroud body from an inlet to an outlet. The position of the inlet and outlet doors may be adjusted (e.g., simultaneously) to change the airflow through the shroud body, and to thereby change the dissipation of heat from the operating engine via this airflow.

A general purpose engine includes: a crankcase to support an engine rotary shaft; a cylinder unit extending from the crankcase in a direction perpendicular to an axis of the engine rotary shaft; a cooling fan fixed to one of opposite ends of the engine rotary shaft; and a fan housing configured to have an air induction opening defined therein for the cooling fan and to cover the crankcase and the cylinder unit from one side of the engine rotary shaft. At a position of the fan housing which is opposed to the cooling fin of the cylinder unit, a cleaning access window is defined. The cleaning access window is covered by a debris covering that is capable of being selectively opened and closed. The debris covering has one end portion engaged with the fan housing and the other end portion removably mounted on the fan housing by a magnetic body.