A crankshaft in which vibrations can be damped effectively without changing a design of a crankcase. The crankshaft comprises a first crank section located at one end of the crankshaft, and a second crank section located at the other end of the crankshaft. In the first crank section, a mass of a first inner balance weight is greater than a mass of a first outer balance weight. In the second crank section, a mass of a second inner balance weight is greater than a mass of a second outer balance weight.

A crankshaft in which vibrations can be damped effectively without changing a design of a crankcase. The crankshaft comprises a first crank section located at one end of the crankshaft, and a second crank section located at the other end of the crankshaft. In the first crank section, a mass of a first inner balance weight is greater than a mass of a first outer balance weight. In the second crank section, a mass of a second inner balance weight is greater than a mass of a second outer balance weight.

A cylinder head includes an intake-side wall part (1a) that upwardly extends from a cylinder head lower surface (lb) coupled to a cylinder block; a port circumferential wall part (4) that forms therein an intake port (3) communicating with a combustion chamber (2) of an engine; an outer longitudinal rib (14) that projects from an outer surface of the port circumferential wall part (4) on a side of the cylinder head lower surface (lb); and a boss part (13) that is bulged from the intake-side wall part (1a) on one end portion of the outer longitudinal rib (14). The port circumferential wall part (4) includes a resin part disposed along an inner surface thereof. The outer longitudinal rib (14) extends in a direction away from the intake-side wall part (1a) along a flow direction of intake air flowing inside the intake port (3). The boss part (13) includes a hole part (13a) that discharges gas in the intake port (3) when injection molding of the resin part is carried out.

A cylinder head includes an intake-side wall part (1a) that upwardly extends from a cylinder head lower surface (lb) coupled to a cylinder block; a port circumferential wall part (4) that forms therein an intake port (3) communicating with a combustion chamber (2) of an engine; an outer longitudinal rib (14) that projects from an outer surface of the port circumferential wall part (4) on a side of the cylinder head lower surface (lb); and a boss part (13) that is bulged from the intake-side wall part (1a) on one end portion of the outer longitudinal rib (14). The port circumferential wall part (4) includes a resin part disposed along an inner surface thereof. The outer longitudinal rib (14) extends in a direction away from the intake-side wall part (1a) along a flow direction of intake air flowing inside the intake port (3). The boss part (13) includes a hole part (13a) that discharges gas in the intake port (3) when injection molding of the resin part is carried out.

In some embodiments, a fuel rail for a two-stroke internal combustion engine includes a fuel rail body, a fuel inlet component integrated within the fuel rail body as a one-piece component and in fluidic contact with a fuel line, one or more fuel exit ports in fluidic contact with a cylinder of a combustion engine, and one or more fasteners adapted to secure the fuel rail body to a cylinder wall of the cylinder of the combustion engine

In some embodiments, a fuel rail for a two-stroke internal combustion engine includes a fuel rail body, a fuel inlet component integrated within the fuel rail body as a one-piece component and in fluidic contact with a fuel line, one or more fuel exit ports in fluidic contact with a cylinder of a combustion engine, and one or more fasteners adapted to secure the fuel rail body to a cylinder wall of the cylinder of the combustion engine

Systems, apparatus, and methods are disclosed that include a divided exhaust engine with at least one pair of primary EGR cylinders and a plurality of pairs of non-primary EGR cylinders. The pair of primary EGR cylinders can be connected to an intake with an EGR system that lacks an EGR cooler. In another embodiment, the cylinder pairs include exhaust flow paths that join in the cylinder head to form a common exhaust outlet for each cylinder pair in the cylinder head that is connected directly to the EGR system or to the exhaust system without an exhaust manifold.

A detection apparatus for detecting a cam angle of a 4-stroke multi-cylinder engine in which explosion intervals are unequal intervals, includes a detection target member configured to rotate in synchronism with a camshaft, and first and second cam angle sensors configured to detect rotation of the detection target member. The detection target member includes a plurality of first detection target portions arranged, at equal pitches, as many as the number of cylinders of the multi-cylinder engine. The second cam angle sensor is arranged while being shifted in the rotation direction with respect to the first cam angle sensor such that any one of detection signals of the plurality of first detection target portions by the first cam angle sensor and the second cam angle sensor is output at a timing corresponding to each explosion interval.

A detection apparatus for detecting a cam angle of a 4-stroke multi-cylinder engine in which explosion intervals are unequal intervals, includes a detection target member configured to rotate in synchronism with a camshaft, and first and second cam angle sensors configured to detect rotation of the detection target member. The detection target member includes a plurality of first detection target portions arranged, at equal pitches, as many as the number of cylinders of the multi-cylinder engine. The second cam angle sensor is arranged while being shifted in the rotation direction with respect to the first cam angle sensor such that any one of detection signals of the plurality of first detection target portions by the first cam angle sensor and the second cam angle sensor is output at a timing corresponding to each explosion interval.

A fuel system comprising a fuel tank, a mixing volume configured to mix fuel vapor and air, the mixing volume comprising an outlet configured to be fluidly coupled to an engine, and a fuel vapor line configured to fluidly couple the fuel tank to the mixing volume.