A structural frame is provided. The structural frame includes a bottom surface, first and second cylinder block sidewall engaging surfaces, the first and second cylinder block sidewall engaging surfaces positioned above the bottom surface at a height that is above a centerline of a crankshaft support included in a cylinder block when the structural frame is coupled to the cylinder block.

A two-stroke engine includes a crankcase. A power cylinder extends from the crankcase. The power cylinder selectively fluidly communicates with the crankcase to scavenge the power cylinder. A power piston is reciprocably disposed in the power cylinder. A compressor cylinder extends from the crankcase. The compressor cylinder selectively fluidly communicates with the power cylinder to introduce a pressurized air/fuel mixture into the power cylinder. A compressor piston is reciprocably disposed in the compressor cylinder.

An internal combustion engine is provided with one or more oil drain-back passages. The oil drain-back passage include an entrance into a crankcase via a crankcase breathing window, the crankcase breathing window disposed within and through a bulkhead wall of the crankcase. Thus, each oil drain-back passage may be routed from a cylinder head of the engine to a crankcase breathing window where oil may then enter the crankcase and flow downward into an oil pan coupled to the crankcase.

A small air-cooled internal combustion engine includes an aluminum cylinder block at least partially defining an aluminum cylinder bore, an aluminum cylinder head attached to the aluminum cylinder block, and an aluminum push rod tube separate from and press fit between the aluminum cylinder block and the aluminum cylinder head. The aluminum push rod tube includes a cylinder block end portion, a cylinder head end portion, and a main body extending between the cylinder block end portion and the cylinder head end portion.

An engine block, an engine subassembly, and method for providing and manufacturing an engine block. The engine block includes a plurality of cylinder barrels positioned in the engine block, at least one oil jacket channel formed in the engine block, and an oil inlet port positioned in a peripheral wall of the engine block and connected to the at least one oil jacket channel. The at least one oil jacket channel includes a plurality of curved channel sections. Each curved channel section in the plurality of curved channel sections extends about at least a portion of a circumferential portion of a respective cylinder barrel in the plurality of cylinder barrels. The at least one oil jacket channel extends between adjacent cylinder barrels of the plurality of cylinder barrels in the engine block.

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 internal combustion engine is provided with one or more oil drain-back passages. The oil drain-back passage include an entrance into a crankcase via a crankcase breathing window, the crankcase breathing window disposed within and through a bulkhead wall of the crankcase. Thus, each oil drain-back passage may be routed from a cylinder head of the engine to a crankcase breathing window where oil may then enter the crankcase and flow downward into an oil pan coupled to the crankcase.

A marine engine has a cylinder block with first and second banks of piston-cylinders that are vertically aligned and extend transversely with respect to each other in a V-shape so as to define a valley there between. A crankshaft is caused to rotate by the first and second banks of piston-cylinders. A flywheel is coupled to the upper end of the crankshaft such that rotation of the crankshaft causes rotation of the flywheel. An alternator is located above the cylinder block and coupled to the flywheel such that rotation of the flywheel operates the alternator.

An internal combustion engine according to the invention comprises at least two engine blocks which are coupled to one another and each of which includes at least two cylinders, each cylinder being connected to a common drive shaft via a transmission and a clutch. If there is a problem with one engine block, same can be disconnected from the drive shaft so that the engine can continue to operate by means of the other engine block.

An improved surface activation technique improves the adhesion of thermal spray coatings, which is useful for engine cylinder bores. The new method includes compressing the cylinder bore surface to create a surface profile on the surface, such as through rolling a roller along the surface. An engine block is also provided, which includes a plurality of cylinder bores, each cylinder bore having an inner surface, and each inner surface having a surface profile that includes a helical groove and other surface profiles formed in the inner surface. A thermal spray coating is formed on the inner surface of each cylinder bore, the thermal spray coating being adhered to the surface profile of the inner surface. A roller assembly for activating the surface is also provided.