Methods and systems are provided for a cylinder head with an exterior wall including a removable camshaft carrier. In one example, a cylinder head includes a camshaft carrier removably couplable to a mount surface of the cylinder head and adapted to form a portion of an exterior wall of the cylinder head while coupled to the mount surface. The camshaft carrier may include a first section removably couplable to the cylinder head and a second section removably couplable to the first section, with the first section and the second section together shaped to receive a camshaft journal.

Systems are provided for a cooling arrangement of an engine. In one example, a system includes a first coolant passage and a second coolant passage arranged in a cylinder bridge between directly adjacent cylinders, wherein the first coolant passage and the second coolant passage are separated from one another.

An internal combustion engine for a motorcycle includes a rear cylinder head, the rear cylinder head being provided with a camshaft, an exhaust rocker arm rocked by the camshaft, an engine valve closed/opened by being push-pressed by the exhaust rocker arm, and a rocker arm shaft swingably supporting the exhaust rocker arm. In the internal combustion engine for the motorcycle, the rear cylinder head is provided separately from a holder member, the holder member being provided adjacently to the rear cylinder head, the camshaft is rotatably supported by the holder member, and the holder member is provided with right and left rear side walls and internal combustion engine supporting portions, the right and left rear side walls supporting the rocker arm shaft, the internal combustion engine supporting portion being supported by a vehicle body frame.

An engine power unit includes a crankcase, a cylinder body, and a cylinder head sequentially stacked and fastened with each other. A cam shaft holder is fastened to the cylinder head to rotatably support a cam shaft of an engine valve operating mechanism. A cylinder head cover covers the cylinder head and the cam shaft holder. Fastening bolts penetrate the cylinder head cover and the cam shaft holder to be screwed into the cylinder head. Pressing surfaces are formed on the inner surface of the cylinder head cover. The pressing surfaces are abutted against and press the cam shaft holder to the cylinder head. Thus, rigidity around the cylinder head is enhanced, and a weight reduction of the power unit is achieved.

An engine includes an output shaft, a cylinder block, a cylinder head, a cap portion, and head bolts. The cylinder block, the cylinder head, and the cap portion are fastened together with the head bolts. The cylinder block includes a cylinder portion and a plurality of output shaft supporting portions. When an outer wall face of at least one of the plurality of output shaft supporting portions is viewed along an output shaft axial direction, the outer wall face includes a first rib diagonally extending from a supporting portion of the output shaft toward one of two head bolt holes.

An internal combustion engine and related components and methods of manufacturing and implementing an internal combustion engine and related components. The internal combustion engine includes a base, a cylinder block mounted onto the base, a cylinder head mounted onto the block, and a structural overhead member mounted onto the cylinder head, such that the cylinder head is positioned between the cylinder block and the structural overhead member. At least one through-bolt positioned in a through-bolt opening, the through-bolt opening extending from the base to the structural overhead member through the cylinder block and the cylinder head to couple the base, the cylinder block, the cylinder head and the structural overhead member together.

Methods and systems are provided for a cylinder head with an exterior wall including a removable camshaft carrier. In one example, a cylinder head includes a camshaft carrier removably couplable to a mount surface of the cylinder head and adapted to form a portion of an exterior wall of the cylinder head while coupled to the mount surface. The camshaft carrier may include a first section removably couplable to the cylinder head and a second section removably couplable to the first section, with the first section and the second section together shaped to receive a camshaft journal.

An internal combustion engine includes a block having at least one cylinder, a head joined to the block, a fastener coupling the head to the block and comprising a shank extending along a fastener axis between the block and the head, a fluid conduit extending parallel to the fastener axis and having an inner surface defined by the shank, and a seal fixed to the shank sealing the fluid conduit to prevent a fluid disposed in the fluid conduit from flowing across the seal in the fluid conduit.

A cooling structure of an internal combustion engine includes a thermostat provided to switch circulation between a radiator passage and a bypass passage in an engine body, to thereby enable acceleration of early warming up via the bypass passage without impairing the external appearance or increasing the size of the internal combustion engine. The cooling structure also includes an in-cylinder-block fluid passage partitioned up and down in an axial direction of a cylinder axis into an in-cylinder-block upper fluid passage and an in-cylinder-block lower fluid passage by a partition wall. The bypass passage is partially composed of the in-cylinder-bock lower fluid passage.

An internal combustion engine includes a cylinder head and a cylinder block. The cylinder head includes a first boss cylinder head conduit portion and a first boss cylinder head cavity portion. The first boss cylinder head conduit portion is configured to receive a first fastener without threadably engaging the first fastener. The first boss cylinder head conduit portion has a first diameter. The first boss cylinder head cavity portion is aligned with the first boss cylinder head conduit portion. The first boss cylinder head cavity portion is configured to receive the first fastener without threadably engaging the first fastener. The first boss cylinder head cavity portion has a second diameter greater than the first diameter. The cylinder block is coupled to the cylinder head. The cylinder block includes a first boss cylinder block threaded portion.