An internal combustion engine (10) fitted with a carburetor (40) is provided with a fire-resistant cover member (62) having a front wall (65A) facing an air inlet port (44) of the carburetor, and a breather tube (60) having an inlet end (60A) connected to a crank chamber (28) of the internal combustion engine main body, and an outlet end (60B) supported by the cover member at a position located between the front wall and the carburetor.

In this air intake apparatus for an internal combustion engine, an external gas passage includes external gas introduction nozzles that introduce external gas into air intake pipes, and a length of each of the external gas introduction nozzles in a direction in which the external gas introduction nozzles extend is larger than an equivalent diameter of an exit of each of the external gas introduction nozzles.

Internal combustion engines having an external mixture formation and compensation tank for avoiding reignition. An internal combustion engine is provided having an external mixture formation including at least one exhaust system, at least one intake system, the intake system including at least one intake manifold, at least one throttle valve, at least one mixture forming device, at least one compensation tank, and at least one air filter.

A first fuel storage portion is disposed on the upstream side of a fuel supply device of an engine so as to be contiguous with an air-intake passage of the fuel supply device. A blow-back suppression plate for suppressing blow-back from the air-intake passage is disposed between a filter element and the first fuel storage portion of an air cleaner. A suction-back passage is formed such that fuel accumulated in a fuel accumulation portion in the air cleaner is suctioned back through the suction-back passage into the air-intake passage. The suction-back passage allows communication between the fuel accumulation portion in the air cleaner and a suction-back port formed at the downstream-side end of the first fuel storage portion.

Intake ports include a second port configured such that a flow rate of flowing gas is adjusted via a swirl control valve. When a surge tank is viewed in a cylinder axis direction, first and second branched passages are connected with a space being interposed therebetween in a cylinder array direction, and are connected to the surge tank on extension lines, each of which extends from an upstream end portion of an independent passage connected to the second port to an opposite side of each cylinder.

An air intake passage (30) has a third passage (37) that connects an intercooler (36) and a bottom portion of a surge tank (38) such that the intercooler (36) is positioned below the surge tank (38). A pair of wall portions (71, 72) configured to catch moisture is formed in a section from an upstream end portion of the third passage (37) to a connected portion between said third passage (37) and the surge tank (38).

A mounting bracket for a handlebar of a discontinued All-Terrain Vehicle (ATV) is provided. The mounting bracket includes a U-shape body, wherein a lower portion of both legs of the U-shape body are tilted at an approximately thirty-degree degree angle relative to a remaining portion of the mounting bracket; and a plurality of mounting holes only provided along said lower portions.

Check valves are disclosed and include a housing defining an internal cavity having a first seat and a second seat, and a seal member within the internal cavity translatable between a closed position against the first seat and an open position against the second seat. The second seat has a middle axis transverse to a plane of a longitudinal cross-section of the housing and has a shortest finger positioned to either the left or to the right of the middle axis. The seal member is seatable against the second seat at an angle or in a deflected position against the plurality of fingers, thereby defining a longer distance of travel to reach the closed position for a portion of the check valve disc that is associated with the position of the shortest finger relative to other portions of the check valve disc.

To provide an intake manifold which can reliably prevent the step from being formed in the inner wall surface of the intake passage (15) while having provided therein the fitting holding portion (32) for fitting and holding the flame arrester (25) in the axial direction, the intake manifold (10) includes a base member (21), a cover member (22) and a flame arrester (25) having a flame suppression structure. Between the flame arrester (25) and the radical stepped surface (31b) of the recessed body portion (31) is provided a retaining rectifying member (23) that prevents the flame arrester (25) from coming off with respect to the fitting holding portion (32) and forms a third inner peripheral surface (23a) continuous without a step from an opening portion on the other end side (25b) of the flame arrester (25) to the base side second inner wall surface (31c).

An engine intake structure for an internal combustion engine (13) of a vehicle (1) comprises a vehicle body opening (6) formed in a front part of an engine room (3) of the vehicle, an intake duct member (22) defining an air inlet (22A) facing in a forward direction and an air passage extending rearward from the air inlet, the air inlet being positioned higher than the vehicle body opening, and a flow obstructing member (60) typically consisting of an auxiliary device such as a horn positioned in a straight path extending from the vehicle body opening to the air inlet.