Disclosed is a new air intake system of an engine including a blow-by gas flow line configured to allow blow-by gas to flow into an intake manifold by recirculating the blow-by gas using a pressure difference according to load of the engine, an intake gas supply line configured to allow intake gas to flow therethrough, the intake gas supply line including a throttle valve configured to control an amount of the intake gas and a turbocharger configured to compress the intake gas, a new air supply line branched from the intake gas supply line and connected to the crankcase, the new air supply line allowing new air to selectively flow into the crankcase, and a new air bypass line configured to allow, when a part of the intake gas is selectively bypassed by the pressure difference, the part of the intake gas to flow into the crankcase.

A motorcycle supercharger (42) pressurizes intake air (I) for a combustion engine (E). The supercharger (42) includes a centrifugal impeller (50) and an impeller casing (52) which covers the impeller (50). The impeller casing (52) includes an outer peripheral wall (84) located radially outward of the impeller (50) and a side wall (86) located axially outward of the impeller (50). Reinforcing first and second side wall ribs (94, 96) are provided at the side wall (86) of the impeller casing (52).

The disclosure concerns air cleaners. Preferred air cleaners are shown which include a housing and a removable and replacement primary filter cartridge. Optional and advantageous features are shown. The preferred primary filter cartridge is conical in shape. A preferred optional safety or secondary filter cartridge is shown. Preferred methods of assembly and use are provided.

Apparatuses, systems and methods are disclosed including apparatus for a ventilation system for supplying air to a crankcase of an internal combustion engine. The apparatus can optionally include a housing, an air filter, a lid and a pressure relief valve. The housing can form a cavity and having an inlet and an outlet therein. The inlet communicates with the cavity and is offset from a centerline axis of the housing. The air filter can be received by the cavity. An outer circumference of the air filter can be oriented at an angle that is substantially tangent to the inlet. The lid can be attachable to and removable from the housing for selectively accessing the air filter. The pressure relief valve coupled to the housing and in fluid communication with the cavity.

An internal combustion engine includes: a cylinder having a combustion chamber formed at an upper side thereof and accommodating a piston to be reciprocally movable; a crankcase provided below the cylinder and accommodates a crankshaft; and a blow-by gas passageway recirculating blow-by gas, which leaks into the crankcase from the combustion chamber, to the combustion chamber through an intake system, in which an inner surface portion of the crankcase is provided with a blow-by gas intake part, and the blow-by gas intake part includes a protruding portion protruding in a direction in which the crankshaft extends, and the intake port opened in the protruding direction is formed at a tip end portion of the protruding portion.

The disclosure concerns air cleaners. Preferred air cleaners are shown which include a housing and a removable and replacement primary filter cartridge. Optional and advantageous features are shown. The preferred primary filter cartridge is conical in shape. A preferred optional safety or secondary filter cartridge is shown. Preferred methods of assembly and use are provided.

A supercharging system for a combustion engine of a motorcycle includes a supercharger which pressurizes intake air and supplies the intake air to the combustion engine, an air intake chamber which is connected to downstream of the supercharger, a relief passage which relieves the high-pressure intake air within the air intake chamber, and a relief valve which is provided on the relief passage. The air intake chamber is disposed above the combustion engine, and the relief passage is disposed below an upper end of the air intake chamber. The relief passage is connected to a front surface of the air intake chamber.

An engine (E) of a saddle-riding type vehicle has an engine case that is substantially L-shaped by a cylinder block (42) being protruded upward from an upper face of a front portion of a crank case (40). An air cleaner (55) is disposed rearwardly of the cylinder block (42) and above the crank case (40). An outlet (72) through which blow-by gas (G) in the engine (E) is discharged is formed in the rear portion of the cylinder block (42). A case body (84) of the air cleaner (55) has a blow-by gas introduction port (86) through which the blow-by gas (G) is introduced into the air cleaner (55). The outlet (72) of the cylinder block (42) and the blow-by gas introduction port (86) of the case body (84) are connected by a connecting pipe (90). The blow-by gas introduction port (86) is disposed close to the cylinder block (42).

A vehicle includes: an internal combustion engine used for traveling and including a crank case and a cylinder block connected to the crank case; an air cleaner that purifies intake air to be supplied to the internal combustion engine; and a breather tube that is connected to the crank case and the air cleaner and supplies a gas in the crank case toward the air cleaner. A connection portion between the breather tube and the crank case is located at a first side of a vehicle width direction middle of the cylinder block in a vehicle width direction.