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.

A carburetor air fuel mixture device is provided. The device includes a stem ending in a shank; a thread portion along the stem adjacent the shank; a spring slid over the shank; and a O-ring, wherein the spring and the O-ring are dimension so that a circumference of the spring slides in an air fuel mixture opening of a carburetor, and wherein the O-ring seals said air fuel mixture opening.

An air intake circuit for a heat engine is intended to be positioned between an air compression element and at least an upper portion of a hollow combustion chamber in a cylinder head of the engine. The air intake circuit includes the cylinder head, an air intake manifold, and at least one air intake duct. The circuit also includes at least one concave receptacle turned towards the outside of the engine, housed in a cavity of the cylinder head, and connected to a tubular element pushed into the at least one air intake duct.

An intake passage includes: a main intake passage provided with a throttle valve and extending from one side toward the other side along a cylinder bank; and a bypass passage provided with an EGR valve and connected to a part of the main intake passage located toward the other side with respect to the throttle valve. The bypass passage extends from a branch of the main intake passage toward the one side and then turns back and extends toward the other side. The EGR valve is located in a part of the bypass passage extending toward the other side and overlapping with a part extending from the branch to the one side.

An intake duct structure of a motorcycle includes front forks disposed on both of right and left sides of a head pipe of a body frame and a main frame extending obliquely backward and downward from the head pipe, wherein the intake duct structure extends from a front end of the motorcycle toward the head pipe and is formed in such a manner that an interfered area where a rotational orbit of the front forks at a time of steering overlaps the intake duct structure is elastically deformable.

An intake manifold that allows air to flow through the intake manifold, engine, and exhaust from the engine, until the engine is cooled to a desired temperature.

An intake structure of an engine includes an intake manifold as an engine side-part intake member that is provided on an intake side-surface of a cylinder head and connected to an intake system, which includes a first air cleaner as an engine upper-part intake member on an upper-part of the engine body; an intake opening member including an air inlet, an intake air passage guiding air sucked by the member through the first air cleaner to the intake manifold; a resonator as one of an engine upper-surface intake members provided on an upper surface of the engine body and nearer an exhaust system than and adjacent to the first air cleaner; and an intake manifold connected to the side-surface as an engine side-part intake member.

An intake manifold for an engine is arranged between a cylinder head port mounted on a cylinder head and a surge tank. The intake manifold includes: a first runner including a first end provided with a first inlet portion connected to the surge tank, and a second end that is branched at a position spaced apart from the first inlet portion by a predetermined distance and is respectively connected to first and fourth runners formed in the cylinder head port; and a second runner including a second end provided with a second inlet portion connected to the surge tank at a position adjacent to the first inlet portion, and a second end that is branched at a position spaced apart from the second inlet portion by a predetermined distance and is respectively connected to second and third runners formed in the cylinder head port.

An intake manifold for an engine is arranged between a cylinder head port mounted on a cylinder head and a surge tank. The intake manifold includes: a first runner including a first end provided with a first inlet portion connected to the surge tank, and a second end that is branched at a position spaced apart from the first inlet portion by a predetermined distance and is respectively connected to first and fourth runners formed in the cylinder head port; and a second runner including a second end provided with a second inlet portion connected to the surge tank at a position adjacent to the first inlet portion, and a second end that is branched at a position spaced apart from the second inlet portion by a predetermined distance and is respectively connected to second and third runners formed in the cylinder head port.

A system for enhancing performance of a carburetor engine and peripherals of an all-terrain vehicle.