An engine (E) includes a crankcase body (19) including a bottom plate (19a) and a tubular portion (19c), a crankcase cover (20) covering a case opening portion (19b) of the crankcase body (19), a crankshaft (2), a cylinder base portion (21a) located inside the crankcase body (19), a cylinder block (21b) located outside the crankcase body (19), and a camshaft (25) located inside the crankcase body (19) and between the bottom plate (19a) and cylinder base portion (21a). The crankcase body (19) has the bottom plate (19a) detachably attached to the tubular portion (19c).

An internal combustion engine (10) fitted with a carburetor (40) is provided with a fire-resistant cover member (62) having a front wall (65A) facing an air inlet port (44) of the carburetor, and a breather tube (60) having an inlet end (60A) connected to a crank chamber (28) of the internal combustion engine main body, and an outlet end (60B) supported by the cover member at a position located between the front wall and the carburetor.

An apparatus comprising a cylinder for an internal combustion engine having at least one combustion chamber and a squish area disposed at or around a base of the at least one combustion chamber, wherein the at least one combustion chamber comprises a paraboloidal cavity.

An engine is provided with: a crank case that has a first crank shaft insertion hole and a second crank shaft insertion hole along the vertical direction; a crank shaft that is inserted into the first and second shaft insertion holes; and a cylinder unit that extends in the front-rear direction from the crank case. The cylinder unit is provided with a cylinder base that is positioned inside the crank case, and a cylinder block that is positioned outside the crank case. The cylinder unit is detachably attached to the crank case.

An engine (E) includes a crankcase body (19), a crankcase cover (20) covering a case opening portion (19b) of the crankcase body (19), a crankshaft (2), a cylinder base portion 21a located inside the crankcase body (19), a cylinder block (21b) located outside the crankcase body (19). The crankcase cover (20) is detachably attached to an upper portion of the crankcase body (19).

In an internal combustion engine, a breather chamber can be formed without increasing the number of component parts. The internal combustion engine (1) comprises an engine block (30) defining a cylinder (2); a case member (19) fastened to a lower part of the engine block to define a crank chamber (4) jointly with the engine block; and a bearing member (50) fastened to the engine block in the crank chamber to rotatably support a crankshaft; wherein the engine block is provided with a central recess (134) formed in a part thereof to which the bearing member is fastened, a blow-by gas inlet passage (112, 116, 121) communicating the central recess with the crank chamber, and a blow-by gas return passage (122, 118) forming a part of a passage communicating the central recess with an intake device, the central recess and the bearing member jointly defining a central breather chamber.

Herein described is a two-stroke internal combustion engine (100), comprising: a cylinder (135) having a pre-set central axis (B); a piston (145) slidably coupled to the cylinder (135) and suitable to divide the interior volume thereof into two distinct chambers, including a combustion chamber (150) and a pumping chamber (155); an intake duct (160) communicating with the pumping chamber (155); an exhaust duct (170) communicating with the combustion chamber (150); and at least one scavenging duct (180) suitable to place the pumping chamber (155) in communication with the combustion chamber (150); wherein said scavenging duct (180) comprises a terminal portion (190) leading to the combustion chamber (150) which extends with configuration diverging from an inlet section (200) up to an outlet section (205) obtained on a lateral surface of the cylinder (135).

An internal combustion engine (10) fitted with a carburetor (40) is provided with a fire-resistant cover member (62) having a front wall (65A) facing an air inlet port (44) of the carburetor, and a breather tube (60) having an inlet end (60A) connected to a crank chamber (28) of the internal combustion engine main body, and an outlet end (60B) supported by the cover member at a position located between the front wall and the carburetor.

An apparatus comprising a cylinder for an internal combustion engine having at least one combustion chamber and a squish area disposed at or around a base of the at least one combustion chamber, wherein the at least one combustion chamber comprises a paraboloidal cavity.

A cylinder for an internal combustion engine comprising at least one combustion chamber and a squish area disposed at or around a base of the at least one combustion chamber, wherein the at least one combustion chamber comprises a paraboloidal cavity.