Abstract: A motorcycle includes an engine configured to expel an exhaust from combustion chambers of cylinders in a cylinder head through exhaust ports. Each of the cylinders is provided with a recessed portion provided in an exhaust passage wall surface in a central portion of an exhaust passage of a corresponding exhaust port. This makes it possible to maintain flow rate and flow velocity of the exhaust gas, and to decrease exhaust loss. As a result, it is possible to increase engine torque by use of a simple structure. In addition, no restriction is imposed on the layout of parts around the engine, because the recessed portions are provided in the exhaust ports.

Abstract: A motorcycle includes an engine configured to expel an exhaust from combustion chambers of cylinders in a cylinder head through exhaust ports. Each of the cylinders is provided with a recessed portion provided in an exhaust passage wall surface in a central portion of an exhaust passage of a corresponding exhaust port. This makes it possible to maintain flow rate and flow velocity of the exhaust gas, and to decrease exhaust loss. As a result, it is possible to increase engine torque by use of a simple structure. In addition, no restriction is imposed on the layout of parts around the engine, because the recessed portions are provided in the exhaust ports.

Abstract: An injector mounting structure for a V-type internal combustion engine includes an intake manifold arranged in a V-bank. A fuel supply pipe extends linearly in parallel to a crankshaft and is disposed in the V-bank. A pair of injectors are branched in an inverted V-shape in side view from the direction of the axial line of the fuel supply pipe from two branch portions P, Q apart from each other in the direction of the axial line of the fuel supply pipe and extend in parallel to each other and obliquely at an acute angle ? with respect to a segment PQ connecting the two branch portions P, Q in top view. The injectors are mounted by fitting distal end portions of the pair of injectors respectively into mounting holes formed on air-intake pipes of the intake manifold on the respective sides.

Abstract: An injector mounting structure for a V-type internal combustion engine includes an intake manifold arranged in a V-bank. A fuel supply pipe extends linearly in parallel to a crankshaft and is disposed in the V-bank. A pair of injectors are branched in an inverted V-shape in side view from the direction of the axial line of the fuel supply pipe from two branch portions P, Q apart from each other in the direction of the axial line of the fuel supply pipe and extend in parallel to each other and obliquely at an acute angle ? with respect to a segment PQ connecting the two branch portions P, Q in top view. The injectors are mounted by fitting distal end portions of the pair of injectors respectively into mounting holes formed on air-intake pipes of the intake manifold on the respective sides.