Abstract: A saddle riding vehicle includes: a body frame; a fuel tank; an upright internal combustion engine; a fuel injection device; and a high-pressure fuel pump. The high-pressure fuel pump is configured to be driven by one of an intake-side camshaft and an exhaust-side camshaft. The high-pressure fuel pump is mounted on an upper surface of a cylinder head cover in an attitude inclined rearward toward the other of the camshafts. The high-pressure fuel pump can thus be protected from disturbances from the sides, and the length of a high-pressure pipe for feeding fuel from the high-pressure fuel pump to the fuel injection device can be shortened. The vehicle protects the high-pressure fuel pump from disturbances from the sides, and prevents acceleration of vaporization of fuel by reducing heat which the high-pressure fuel pump receives from the cylinder block.

Abstract: An internal combustion engine includes an auxiliary chamber bulkhead, the auxiliary chamber bulkhead including: a peripheral wall portion that is inserted in a vertical hole extending from a combustion chamber along a reference axis and that is in contact with an inner wall of the vertical hole about the reference axis; and a bottom wall portion that is continuous from the peripheral wall portion and that bulges from the vertical hole toward the combustion chamber, the peripheral wall portion and the bottom wall portion defining an auxiliary chamber that communicates with the combustion chamber. An ignition plug is disposed above the peripheral wall portion along the reference axis. A fuel injection valve is disposed in a position inclined with respect to the reference axis toward an opening formed in an inner surface of the peripheral wall portion.

Abstract: A saddle riding vehicle includes: a body frame; a fuel tank; an upright internal combustion engine; a fuel injection device; and a high-pressure fuel pump. The high-pressure fuel pump is configured to be driven by one of an intake-side camshaft and an exhaust-side camshaft. The high-pressure fuel pump is mounted on an upper surface of a cylinder head cover in an attitude inclined rearward toward the other of the camshafts. The high-pressure fuel pump can thus be protected from disturbances from the sides, and the length of a high-pressure pipe for feeding fuel from the high-pressure fuel pump to the fuel injection device can be shortened. The vehicle protects the high-pressure fuel pump from disturbances from the sides, and prevents acceleration of vaporization of fuel by reducing heat which the high-pressure fuel pump receives from the cylinder block.

Abstract: An internal combustion engine includes an auxiliary chamber bulkhead, the auxiliary chamber bulkhead including: a peripheral wall portion that is inserted in a vertical hole extending from a combustion chamber along a reference axis and that is in contact with an inner wall of the vertical hole about the reference axis; and a bottom wall portion that is continuous from the peripheral wall portion and that bulges from the vertical hole toward the combustion chamber, the peripheral wall portion and the bottom wall portion defining an auxiliary chamber that communicates with the combustion chamber. An ignition plug is disposed above the peripheral wall portion along the reference axis. A fuel injection valve is disposed in a position inclined with respect to the reference axis toward an opening formed in an inner surface of the peripheral wall portion.