An internal combustion engine includes a one-piece cylinder block casting, a flywheel supported for rotation at a front block end, and a back gear train supported for rotation at a back block end. Cast-in pump inlet and outlet passages are formed in the cylinder block casting and open in a pump mounting face at the back block end. An oil pump is clamped to the pump mounting face and includes a pump inlet and a pump outlet fluidly connected, respectively, to the cast-in pump inlet passage and the cast-in pump outlet passage.

A quantitative one-way oil gas lubricant system and a method for a 4-stroke engine, including a preceding stage quantitative oil intake orifice that is connected to a lubricant case on a wall of a crankcase of the 4-stroke engine, and a final stage quantitative airflow orifice disposed at a cylinder cover of the 4-stroke engine, are provided. A diameter of the preceding stage quantitative oil intake orifice D.sub.1 and a diameter of the final stage quantitative airflow orifice satisfy an equation: D.sub.1/D.sub.3=0.8-1.5, wherein a one-way connected oil gas lubricant channel is disposed between the preceding stage quantitative oil intake orifice and the final stage quantitative airflow orifice. A lubricant oil sucked from the preceding quantitative oil intake orifice by the crankcase flows along the oil gas lubricant channel and lubricates the engine parts that the channel passes through in turns. Finally, a minute quantity of waste oil gas that flows out from the final stage quantitative airflow orifice is introduced into a cylinder of the 4-stroke engine and is to be burned completely. The supply quantity of the lubricant oil may be controlled, and no extra lubricant oil gas may flow out from the final stage quantitative airflow orifice, therefore, the quantitative and one-way lubricating is realized.

An engine assembly includes a small air-cooled engine and a dry sump lubrication system including an external oil reservoir, wherein the dry sump lubrication system has an overall oil capacity that provides at least five hundred hours of engine oil life.

A polyamide resin composition contains a polyamide resin and an inorganic filler. 90 mass % or more of polyamide 66 is contained relative to 100 mass % of the polyamide resin. The inorganic filler content is ≥30 mass % relative to 100 mass % of the composition. The composition has a solidifying point of ≥210° C. The composition has a spiral flow value of ≥60 cm when the inorganic filler content is ≥30 mass % and <40 mass %, ≥40 cm when the content is ≥40 mass % and ≤50 mass %, and ≥20 cm when the content is >50 mass % and ≤70 mass %. The composition has a strain of ≤3.8% in a 1000-hour tensile creep test under 120° C. and 60 MPa. The composition has a formic acid relative viscosity (VR) of 30<VR<40.

A polyamide resin composition contains a polyamide resin and an inorganic filler. 90 mass % or more of polyamide 66 is contained relative to 100 mass % of the polyamide resin. The inorganic filler content is ≥30 mass % relative to 100 mass % of the composition. The composition has a solidifying point of ≥210° C. The composition has a spiral flow value of ≥60 cm when the inorganic filler content is ≥30 mass % and <40 mass %, ≥40 cm when the content is ≥40 mass % and ≤50 mass %, and ≥20 cm when the content is >50 mass % and ≤70 mass %. The composition has a strain of ≤3.8% in a 1000-hour tensile creep test under 120° C. and 60 MPa. The composition has a formic acid relative viscosity (VR) of 30<VR<40.

An engine cover member mounting structure, including: an engine body; a peripheral member arranged on an outer wall of the engine body; a cover member arranged between the outer wall and the peripheral member; and a harness routed between the outer wall and the peripheral member, wherein the harness is held on a surface of the cover member.

An engine cover member mounting structure, including: an engine body; a peripheral member arranged on an outer wall of the engine body; a cover member arranged between the outer wall and the peripheral member; and a harness routed between the outer wall and the peripheral member, wherein the harness is held on a surface of the cover member.

An engine block (10) includes a cylinder liner (120) and a resin block (200). The cylinder liner (120) has a metal outer circumferential surface (122). The resin block (200) includes a first portion (210) and a gap (230). The first portion (210) covers the metal outer circumferential surface (122) of the cylinder liner (120). The gap (230) is positioned outside the first portion (210) and defines a water jacket (232).

Systems are provided for cooling a cylinder block via bore bridge cooling passages. In one example, a cylinder block with a bore bridge positioned between a first cylinder and a second cylinder, the cylinder block also including a coolant jacket at least partially surrounding the first cylinder and the second cylinder, has at least one cooling passage positioned within the bore bridge. An inlet of the at least one cooling passage has a larger area than an outlet of the at least one cooling passage and at least a portion of the at least one cooling passage has a non-cylindrical geometry formed by a lost core.

A crank and connecting rod mechanism, comprising at least one piston, which reciprocates within at least one cylinder, comprising: at least one connecting rod, comprising: a piston end pivotally connected to the at least one piston, a crank end; at least one gear set, comprising: a crankpin, the crank end pivotally connected to the crankpin; a crank gear; a crank gear shaft, the crank gear rotatably mounted on the crank gear shaft, the crankpin located between centerline of the crank gear shaft and radius of the pitch circle of the crank gear; a stationary gear, the crank gear meshing with the stationary gear, the crank end driving the crankpin, which drives the crank gear and the crank gear shaft about the stationary gear; the crank pin and the crank end rotating about the stationary gear and following the path of a roulette of a centered trochoid about the stationary gear.