An intake valve for an internal combustion engine is provided. The intake valve includes a valve stem with a hole in the valve stem forming an air channel there through that allows intake air to flow from an intake passage, through the air channel, into a cylinder of the internal combustion engine.

An engine valve having a shaft portion and a head portion expanding in diameter like a head at an edge of the shaft portion, and being to open and close a port provided in a cylinder head, wherein the head portion has a head front surface on a bottom side facing a combustion chamber side, a head rear surface on a top side facing the port side, and an outer peripheral surface of the head portion formed between the head front surface and the head rear surface, and the head portion is provided a mirror-finished mirror portion, and the head portion is provided a mirror-finished mirror portion on the entire area of the head front surface exposed to the combustion chamber and the entire area of the outer peripheral surface exposed to the combustion chamber.

An object of the invention is to provide an internal combustion engine that suppresses a blow-by phenomenon in an overlap period, while allowing for formation of a favorable swirl flow in a combustion chamber. In the internal combustion engine, a housing space is formed in an opening of an exhaust port to the combustion chamber to be more recessed in a cylinder head than an exhaust port-side ceiling surface. A bevel portion of an exhaust valve is placed in the housing space in a valve closed state of the exhaust valve. A valve contact surface is formed on an inner wall surface of the housing space. With regard to an effective passage width of an effective passage that is defined as a linear virtual passage extended from the combustion chamber through the housing space to inside of the exhaust port in a section extended from an intake port side to a bore wall surface side of an exhaust port side, the housing space is formed such that the effective passage width in any location in an intake side space is made smaller than the effective passage width in a corresponding location in an exhaust side space in a slight lifting state of the exhaust valve.

An object of the invention is to provide an internal combustion engine that suppresses a blow-by phenomenon in an overlap period, while allowing for formation of a favorable swirl flow in a combustion chamber. In the internal combustion engine, a housing space is formed in an opening of an exhaust port to the combustion chamber to be more recessed in a cylinder head than an exhaust port-side ceiling surface. A bevel portion of an exhaust valve is placed in the housing space in a valve closed state of the exhaust valve. A valve contact surface is formed on an inner wall surface of the housing space. With regard to an effective passage width of an effective passage that is defined as a linear virtual passage extended from the combustion chamber through the housing space to inside of the exhaust port in a section extended from an intake port side to a bore wall surface side of an exhaust port side, the housing space is formed such that the effective passage width in any location in an intake side space is made smaller than the effective passage width in a corresponding location in an exhaust side space in a slight lifting state of the exhaust valve.

An atomization valve for use as an intake valve in an internal combustion engine that consists essentially of an elongated valve stem with two opposed ends, a valve head located at one of the two opposed ends and formed integrally with the valve stem in which the valve head having an outer rim and a tapered shoulder portion terminating adjacent the stem portion and the tapered shoulder portion having an upper surface bearing a plurality of grooves.

An atomization valve for use as an intake valve in an internal combustion engine that consists essentially of an elongated valve stem with two opposed ends, a valve head located at one of the two opposed ends and formed integrally with the valve stem in which the valve head having an outer rim and a tapered shoulder portion terminating adjacent the stem portion and the tapered shoulder portion having an upper surface bearing a plurality of grooves.

A cylinder head for an internal-combustion engine includes, for each cylinder of the engine, at least one intake duct extending from an inlet located at a lateral face of the head down to an outlet cylindrical mouth and an intake valve associated with each intake duct. The surface of the intake duct has a longitudinal projection for deflecting the flow of air that flows through the intake duct. The projection is configured to provide a deflection of the air flow towards the two sides of the valve stem, so as to substantially reduce the quantity of air that hits the valve stem directly. The projection extends down to the outlet cylindrical mouth, so as to hinder a flow of air through an angular sector of the cross-sectional area of the outlet mouth which angular sector faces towards the lateral face of the cylinder head.

A cylinder head for an internal-combustion engine includes, for each cylinder of the engine, at least one intake duct extending from an inlet located at a lateral face of the head down to an outlet cylindrical mouth and an intake valve associated with each intake duct. The surface of the intake duct has a longitudinal projection for deflecting the flow of air that flows through the intake duct. The projection is configured to provide a deflection of the air flow towards the two sides of the valve stem, so as to substantially reduce the quantity of air that hits the valve stem directly. The projection extends down to the outlet cylindrical mouth, so as to hinder a flow of air through an angular sector of the cross-sectional area of the outlet mouth which angular sector faces towards the lateral face of the cylinder head.

A moment-cancelling, four-stroke engine is disclosed. The engine includes a first cylinder having a first piston and a second cylinder having a second piston, a first crankshaft operably connected to the first piston and a second crankshaft operably connected to the second piston. The first crankshaft rotates in a first direction and the second crankshaft rotates in a second direction that is opposite the first direction to cancel the moments applied to the engine and reduce engine vibration.

A moment-cancelling, four-stroke engine is disclosed. The engine includes a first cylinder having a first piston and a second cylinder having a second piston, a first crankshaft operably connected to the first piston and a second crankshaft operably connected to the second piston. The first crankshaft rotates in a first direction and the second crankshaft rotates in a second direction that is opposite the first direction to cancel the moments applied to the engine and reduce engine vibration.