An air induction system for delivering equal quantities of combustion air to an internal combustion engine has an air box assembly comprising a housing that defines a filter chamber that is configured to receive an air filter assembly, an air inlet that admits the fresh air into the housing and the filter chamber and outlets extending from the housing. The air filter assembly further comprises a filter media disposed between the air inlet and the outlets to define a filtered air chamber on a flow side of the filter media and a partition extending across the filtered air chamber to divide filtered, fresh air passing through the filter media into two flow paths, the divided flows paths exiting the housing and the filtered air chamber through the outlets.

An air intake duct (50) for a motorcycle supplies air taken in through an air inlet (24) in a front portion of a vehicle body to an engine (E) located at a center portion, in a longitudinal direction of the motorcycle, of the vehicle body. The air intake duct (50) includes a duct front (69) having the air inlet (24) formed at a front end thereof, and a duct body (70) removably coupled to a rear end portion of the duct front (69). The duct body (70) extends in the longitudinal direction so as to pass through an outer lateral side of the engine (E) and is removably connected at a rear end portion thereof to an air cleaner (40). In a state in which the duct body (70) is removed from the air cleaner (40), a cleaner element (87) can be attached and removed.

An intake system includes an air cleaner that is disposed above an engine main body mounted on a vehicle body frame and connected to cylinder heads of the engine main body and an air introducing unit for introducing air into an air inlet provided at a lateral part of the air cleaner on at least one side thereof in a vehicle width direction. The air introducing unit has an opened front end and is connected to the air cleaner so as to bend an intake direction from a vehicle front-rear direction to the vehicle width direction. In the air inlet, a plurality of ribs partition the air inlet into plural sections.

A filter assembly includes a conditioning device that conditions a flow of air upstream of a mass air flow sensor. The filter assembly includes a support frame. The filter assembly further includes a filter media coupled to the support frame, the filter media having a dirty side configured to receive a stream of air and a clean side configured to output a stream of air that has been filtered through the filter media. The filter assembly includes a conditioning device coupled to the support frame, the conditioning device positioned in a downstream direction from the clean side of the filter media with respect to the stream of air, the conditioning device offset from the clean side of the filter media by a separation distance.

An engine includes a breather conduit, an intake conduit, and an air filter assembly. The assembly includes a filter element having a top wall, a bottom wall, a first aperture through the bottom wall, a second aperture through the bottom wall, and filter media extending between the top and bottom walls, wherein the first and second apertures are the same shape, the same size, and are equally spaced apart from the center of the bottom wall. The filter assembly also includes a case. The filter element is configured to be received in the case such that the breather conduit and the intake conduit are directed to and from the interior chamber of the filter element, respectively, whereby air filtered by the filter media mixes with unfiltered gases from the breather conduit in the interior chamber of the filter element prior to entering the intake conduit.