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.

Methods and systems are provided for an air intake apparatus. In one example, a system comprises an air filter box rotatably mounted to an intake manifold. The air filter box rotates about an axis angled to a direction of forward vehicle travel.

Internal combustion engine comprising—a first pair of cylinders which accommodate, according to a rectilinear reciprocating motion, relative first pistons operatively associated to a motor shaft rotating around a motor axis disposed in a transverse direction, perpendicular to a longitudinal running direction of an associable vehicle, —a suction system comprising a filter box which delimits a suction volume which houses at least a first front suction duct and at least a first rear suction duct, respectively disposed in an advanced and retracted position in relation to an air/suction mixture inlet direction, each suction duct channelling the air/suction mixture before entering in the respective cylinders, —wherein said first front and rear suction ducts are fixed and have respective mutually different lengths.

There is provided an air cleaner including: an outlet pipe through which air is discharged; an airflow meter that is inserted toward an interior of the outlet pipe through a wall of the outlet pipe; and a flow-regulating member that is formed projecting from an inner surface of the outlet pipe at a side of the airflow meter, the flow-regulating member including an edge that is formed with a peaked shape with respect to the inner surface and that runs along a direction of flow of air, a rear end that is formed at a downstream end of the edge in the direction of flow, and that is shaped cut sharply toward the inner surface and a width-narrowing portion that decreases in width in a circumferential direction of the outlet pipe on progression downstream in the direction of flow.

In an engine that includes a blow-by-gas returning system configured to direct blow-by gas within a crankcase to an intake system through an inside of a head cover, the intake system includes a cover intake-passage disposed at a blow-by-gas outlet of the head cover, and the cover intake-passage communicates with a blow-by-gas passage of the blow-by-gas outlet.

Systems and methods are provided for an air filter device. In one example, the air filter device includes a housing enclosing a filter element positioned in a filter enclosure, the filter element including an outlet in fluidic communication with a downstream intake line and an inlet conduit extending through the housing and delivering air to the filter enclosure, and the inlet conduit including a wall dividing the filter enclosure from the inlet conduit. The air filter device further includes a cover sealingly attached to the wall and a peripheral lip of the housing.

An intake pipe includes a cylindrical pipe main body, a flange, which is provided on an end of the pipe main body in an axial direction and protrudes radially outward about an axis of the pipe main body from an outer surface of the pipe main body, and a chamber forming portion, which is located outside of the pipe main body and defines a chamber. The chamber forming portion is provided to connect the outer surface of the pipe main body and the flange to each other and is integrated with the pipe main body and the flange.

Methods and systems are provided for a heating device. In one example, a system comprises a heat exchanger and an air filter arranged in a common housing, wherein the heat exchanger is configured to receive coolant from a heating device. In one example, the heating device is an electric heating device.

A precleaner system for an air intake system. The precleaner system includes precleaners each having flow paths that induce a rotation to air flow and separate out particulate matter. The particulate matter is ejected from an outlet port in each of the flow paths and out of a dust ejector. The precleaned air is collected into a plenum from each of the precleaners. The precleaned air can flow from the plenum to a precleaner system outlet and the precleaned air can be received by an air intake system. A cover can be used to block air flow through one of the precleaners to tune the precleaner system to the desired airflow.

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.