A pump shaft support structure includes: a crankcase body which rotatably supports a crankshaft of an engine; a pump shaft which interlockingly rotates with the crankshaft; a crankcase cover which covers the crankcase body; a pump cover which is coupled to the crankcase cover to define a pump chamber therebetween; and a pump rotor which is disposed in the pump chamber and engages with the pump shaft. The pump shaft includes: a supported section which is rotatably supported by the pump cover on the other side of the pump chamber from the crankcase cover; and an insertion section adjoining the supported section in an axial direction. The pump cover has a through bore which passes the insertion section of the pump shaft therethrough. The insertion section of the pump shaft has a diameter smaller than that of the supported section.

An air-cooled internal combustion engine including a crankshaft rotating about a crankshaft axis, a first cylinder having a first cylinder head, a second cylinder having a second cylinder head, and a blower assembly. The blower assembly includes a blower housing, a first fan, and a second fan. The first fan is positioned proximate the first cylinder and the second fan is positioned proximate the second cylinder. The first fan and the second fan are each received within the blower housing.

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.

An engine includes: a crankshaft disposed vertically; a piston that is connected to the crankshaft via a connecting rod and reciprocates in a cylinder; a cylinder head forming a combustion chamber of the cylinder at an end face of a movable portion of the piston; an intake valve and an exhaust valve disposed at the cylinder head, the intake valve being configured to take in fuel-air mixture, which is a mixture of fuel and air, the exhaust valve being configured to exhaust the fuel-air mixture; a low-rotation rocker arm (rocker arm) that drives the intake valve and the exhaust valve by rotation of a cam shaft; and a rocker shaft that supports the low-rotation rocker arm such that the low-rotation rocker arm is swingable, and an oil holding portion extending in an axial direction of the rocker shaft is provided between the rocker shaft and the low-rotation rocker arm.

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 machine includes a prime mover having a power take-off, a chassis configured to support at least an operator and the prime mover, a subframe pivotally coupled to the chassis about a pivot axis at a first location, at least one drive device configured to drive wheels of the machine, a drive belt and pulley arrangement. The subframe is further coupled to the chassis via at least one suspension device at a second location. The at least one drive device is driven by the prime mover and is coupled to the subframe. The pulley arrangement is configured to direct the drive belt from the power take-off of the prime mover to at least one drive pulley on the at least one drive device. The pulley arrangement comprises an idler pulley having a diameter and a rotational axis. The idler pulley is coupled to the chassis such that the rotational axis is spaced from the pivot axis by no greater than 1.5 times the diameter.

An OHV engine includes V-shaped banks, a crank shaft, a cam shaft connected to the crank shaft, a mechanical supercharger located between the V-shaped banks, and a power transmission supported by the cam shaft and that connects the crank shaft to the mechanical supercharger. The power transmission includes a gear mechanism with a gear ratio not greater than a predetermined value, and includes a first gear supported rotatably by the cam shaft and that rotates based on an output from the crank shaft, a second gear provided on a rotation shaft of the mechanical supercharger, and an idle gear that connects the first and second gears with each other. Cylinders are offset with respect to a center of the crank shaft on an anti-thrust side of the cylinders, and the mechanical supercharger is also offset with respect to a center of the crank shaft on the anti-thrust side. Cylinder heads are provided with oil cooling paths adjacent respective spark plugs.

An outboard motor (10) includes a V-engine (20) having a left bank (BL) and a right bank (BR) extending obliquely toward a rear left side and a rear right side, respectively, relative to a crankshaft (21) extending in a vertical direction. An intake device (18) is provided between the left bank and the right bank, and catalyst devices (62L, 62R) that treat exhaust gas are disposed rearward of cylinder heads (24L, 24R) of the left bank and the right bank.

An engine includes a crankshaft and a timing gear to be attached to the crankshaft so as to rotate integrally with the crankshaft. A fitting projection is provided on either one of the crankshaft and the timing gear, and a fitting recess to be fitted with the fitting projection, and erroneous-assembling prevention ribs to sandwich the fitting recess in a circumferential direction are provided on the other one of the crankshaft and the timing gear.

An engine is provided with: an engine body; and a top cover that covers the engine body, wherein at least a pair of engaging claws are provided to lateral walls, on both sides, of the top cover so as to extend downward, and a pair of engaging holes with which the engaging claws engage are provided to the engine body side. Each of the engaging claws is provided with a plate section that is provided so as to extend downward, and a bulging section that is provided to the leading end of the plate section and that bulges inward from the plate section, and the bulging section engages with the bottom surface of an inner wall section of the corresponding engaging hole.