A utility vehicle includes: an engine which is a drive source; a catch tank configured to perform a gas-liquid separation of a blow-by gas generated in the engine; a first breather passage configured to deliver the blow-by gas, which is discharged from the engine, to the catch tank; a second breather passage configured to supply a gas component, which has been separated in the catch tank, to an air intake system of the engine; and a return passage configured to return a liquid component, which has been separated in the catch tank, to the engine. The catch tank is disposed above a cylinder head covering. A breather outlet port, with which the first breather passage is fluid connected, and an oil return port, with which the return passage is fluid connected, are formed in an upper surface of the cylinder head covering.

An air intake structure of a saddle riding vehicle disposed on a saddle riding vehicle that includes intake system components above an engine, the engine includes a plurality of cylinders aligned at least in front and rear, the intake system components include: funnels coupled to intake ports of the respective cylinders; and injectors facing openings of the respective funnels, the funnels and the injectors are arranged inside the air box, the air intake structure includes an air filter in a front side with respect to the funnel and the injector disposed in a cylinder in a front side. In the air intake structure of a saddle riding vehicle, the air filter is at least disposed so as to be oriented in a vertical direction in side view, and the air filter has a middle part on which a louver is disposed.

An engine assembly includes an engine, an intake assembly, and an air-oil separator. The engine defines a combustion chamber and a crankcase. The intake assembly includes an intake manifold wherein the intake manifold is in fluid communication with the combustion chamber. The air-oil separator defines an internal passageway having a separator volume and further defining an inlet and outlet in fluid communication with the separator volume. The inlet of the air-oil separator may be in fluid communication with the crankcase while the outlet of the air-oil separator may be in fluid communication with the intake manifold. The air-oil separator further includes a fine separator disposed across the internal passageway proximate to the inlet wherein the fine separator includes a curved backplate and a front plate.

An intake device is provided for the combustion air of a motorcycle, including an air filter box and an air guide intake duct which extends from the air filter box in a defined orientation to an intake chamber and at least sections of which are formed by parts of the air filter box.

An apparatus and a method are provided for an air box configured to cool an engine control unit (ECU) by way of an airstream being communicated to an air intake system of an internal combustion engine of a vehicle. The air box is comprised of a housing to support an air filter within an interior of the housing. An opening in the housing fixedly receives at least one surface of the ECU to transfer heat from the ECU to the airstream. A mount portion within the housing receives the air filter. A conduit to a clean side of the air filter is configured to be coupled with the air intake system. An inlet to the housing is configured to couple with an air inlet duct of the vehicle so as to direct the airstream into the interior of the housing.

In an intake device for an internal combustion engine, a first resonator chamber (61) is defined between a clean side chamber (56) and a peripheral wall (8) of a case (2), and a first communication passage (61B) communicating a dust side chamber (55) with the first resonator chamber is extending along the peripheral wall of the case.

A utility vehicle includes: an engine which is a drive source; a catch tank configured to perform a gas-liquid separation of a blow-by gas generated in the engine; a first breather passage configured to deliver the blow-by gas, which is discharged from the engine, to the catch tank; a second breather passage configured to supply a gas component, which has been separated in the catch tank, to an air intake system of the engine; and a return passage configured to return a liquid component, which has been separated in the catch tank, to the engine. The catch tank is disposed above a cylinder head covering. A breather outlet port, with which the first breather passage is fluid connected, and an oil return port, with which the return passage is fluid connected, are formed in an upper surface of the cylinder head covering.

A container of an all-terrain vehicle includes: a container body including a bottom plate and a front side plate, the front side plate being connected to a front-side edge of the bottom plate, the bottom plate being defined with a first through hole, and the front side plate being defined with a second through hole in communication with the first through hole; a first cover plate detachably arranged at the first through hole; a second cover plate detachably arranged at the second through hole and detachable relative to the first cover plate.

An apparatus and methods are provided for an air cleaner to be mounted onto an air inlet of an internal combustion engine. The air cleaner comprises an air filter that includes a filter medium disposed between a curved base and a cover. The curved base provides an interface between the air filter and the air inlet, and comprises a shape that provides clearance between the curved base and an electric choke installed onto a carburetor comprising the air inlet. The cover secures the air filter and the curved base to the air inlet such that an airstream is drawn through the filter medium and is conducted into the air inlet. A raised portion of the cover is configured to cooperate with the curved base to ensure a desired volume of the airstream is available to the air inlet at substantially all engine speeds.

To optimize fuel supply of an engine with a carburetor during engine operation, a throttle opening degree detection sensor detecting a throttle opening degree and a control unit controlling a valve body variably controlling an opening degree of a fuel discharge part or a fuel supply passage based on a map are included. The map includes a plurality of sections divided based on the throttle opening degree and an opening degree of the valve body set for each section. The opening degree of the valve body set for each section is the opening degree of the valve body at which the engine rotation speed is highest in each section. The control unit controls an electric actuator driving the valve body to achieve the opening degree of the valve body set in a section to which the throttle opening degree detected by the throttle opening degree detection sensor belongs out of the plurality of sections.