Abstract: A friction-bearing assembly is disclosed which comprises a friction bearing and a shaft, the friction-bearing assembly includes a first bearing gap defined between the sliding surface of the friction bearing and the outer surface of the shaft, and a second bearing gap defined between the inside surface of the friction bearing and the outer surface of the shaft, the second bearing gap being at least 10% wider relative to the first bearing gap, to a maximum of 1 mm. The second bearing gap is positioned adjacent the first bearing gap and located in-between a lubricating oil supply and the first bearing gap such that the first bearing gap is supplied with lubricating oil through the second bearing gap.

Abstract: A power unit is described that combines an internal combustion engine and a lubrication system. The internal combustion engine includes a crankcase suction chamber and a transmission case suction chamber. At least one partition separates the crankcase suction chamber from the transmission case suction chamber. The lubrication system supplies lubricant to the internal combustion engine. The lubrication system includes a lubrication tank and a supply line for supplying lubricant to the internal combustion engine. At least one crankcase drainage line extends from the crankcase to drain a fluid from the crankcase suction chamber and transfer the fluid to the transmission case suction chamber. At least one pump operatively connects to one of either the crankcase chamber or the transmission case chamber. By the operation of the at least one pump, a negative pressure within at least one of the crankcase chamber and the transmission case chamber is created.

Abstract: An exhaust valve assembly for a two stroke internal combustion engine having a cylinder with at least one main exhaust port and one auxiliary exhaust port is disclosed. The assembly comprises a main exhaust valve for at least partially closing the main exhaust port, an auxiliary exhaust valve for at least partially closing the auxiliary exhaust port, an actuator for actuating the main exhaust valve and the auxiliary exhaust valve, the actuator including a rotary shaft having a first gear and a second gear, the rotary shaft being operatively connected to the main exhaust valve via the first gear, the rotary shaft being operatively connected to the auxiliary exhaust valve via the second gear, an electric motor operatively connected to the rotary shaft for rotating the rotary shaft.

Abstract: An internal combustion engine has a power unit case having a crankcase, a first housing flange and a second housing flange. The crankshaft axis and the output shaft axis define a reference plane. An oil pump has an oil pump shaft, having an oil pump shaft axis, disposed at least partially in an oil pump chamber. A normal projection of the oil pump shaft axis onto the reference plane is located between the crankshaft axis and the output shaft axis. A first housing cover is mounted to the first housing flange on a first side of the power unit case. A separate oil pump cover is mounted to the second housing flange on the first side of the power unit case to close the oil pump chamber.

Abstract: An internal combustion engine has an engine casing. A shaft, having a shaft axis, is disposed in the engine casing. At least one bearing supports the shaft in the engine casing. A separator wheel is disposed on the shaft for rotation therewith. The separator wheel has a first opening in fluid communication with the crankcase, a second opening, and a channel extending radially from the second opening to the first opening relative to the shaft axis. A suction tube is permanently affixed to a portion of the engine casing. An end of the suction tube has a unitary abutment surface. A gasket is disposed between the unitary abutment surface and the second opening of separator wheel. The gasket is also disposed at least in part on a separating plane of the engine casing.

Abstract: An indexing and braking mechanism for a manual transmission having a shifting mechanism and at least one rotatable drive shaft is disclosed. The mechanism includes an indexing mechanism for controlling movement of the shifting mechanism between at least a first position and a neutral position. The indexing mechanism has a plate having a plurality of notches formed thereon, wherein one notch corresponds to the first position and another notch corresponds to the neutral position. A locking mechanism is provided for selectively limiting movement of one of the at least one rotatable drive shaft. The locking mechanism is adapted to selectively engage the plurality of notches to selectively maintain the indexing mechanism in one of the first position and the neutral position. The locking mechanism includes an indexing lever having a contact surface for contacting the rotatable drive shaft.

Abstract: An all terrain vehicle (“ATV”) is disclosed having a frame with front, rear, right, and left sides. An engine and at least two wheel axes are disposed on the frame. A plurality of wheels are disposed on the at least two wheel axes. The engine includes a cylinder disposed adjacent a crankshaft and a generator operatively connected to the crankshaft. An output shaft, separate from the crankshaft, operatively connects to the engine to transmit power from the engine to at least one of the plurality of wheels through at least one of the wheel axes. The output shaft is disposed between the cylinder and the generator in a plane substantially perpendicular to at least one of the wheel axes.

Abstract: A vehicle includes an engine that powers a wheel through a drive train. The drive train includes a continuously variable transmission (CVT) and toothed gearing disposed between the CVT and the wheel. A release clutch is also disposed between the CVT and the wheel. A controller controls the release clutch so as to disengage the clutch when the engine is not running and engage the clutch when the engine is running. The controller includes a hydraulic cylinder that fluidly connects to the engine's oil system so that engine-generated oil pressure engages the release clutch. Disengagement of the release clutch makes it easier to push the vehicle when the engine is not running, for example, when the engine breaks down.

Abstract: A Crankshaft bearing assembly for supporting a crankshaft for rotation about a crankshaft axis within an engine having an aluminum engine block, the crankshaft bearing assembly including at least one crankshaft bearing divided into a first half and a second half, the first half being integral with the engine block, and the second half being a bearing cap connectable to the engine block. The bearing cap is made of an aluminum alloy having a tensile strength higher than the tensile strength of the engine block.

Abstract: A watercraft includes a shell, a ride plate, an internal combustion engine, and a jet pump. The shell defines a tunnel that extends forwardly from the transom and is defined laterally by the shell. The tunnel is open at its bottom The ride plate mounts to the shell under the tunnel. The engine and jet pump are supported by the ride plate and disposed in the tunnel. The engine drives the jet pump. The engine is cooled by water that continuously flows past the ride plate. The engine, jet pump, and ride plate are installed from below or the behind the shell.

Abstract: A personal watercraft is disclosed with a hull, a seating assembly, and a four stroke internal combustion engine below the seating assembly. The engine has at least one intake valve for each of the combustion cylinder chambers, at least one exhaust valve for each of the combustion cylinder chambers, and a valve actuation assembly located in a cylinder head for operating the intake and exhaust valves. At least one air intake passageway is operatively coupled to the combustion cylinder chambers through the intake valves. An air intake manifold is connected to the cylinder bead and operatively connected to the at least one air intake passageway. The engine also has a supercharger for boosting air to the air intake manifold. The watercraft also includes a propulsion unit, operatively coupled to the crankshaft, which is located on one end of the two ends of the crankcase.

Abstract: A four cycle engine having at least one cylinder unit is disclosed. The engine includes a continuously variable transmission (CVT) connected to the engine on one side of the engine. An air box is also provided that is located on the same side of the engine as the CVT. The engine further includes an intake manifold operatively connected to the air box for connecting the air box to each cylinder unit and a throttle assembly operatively connected to air box and the intake manifold. The intake manifold may have a generally Y-shaped manifold having a connector leg connected to the throttle assembly and a pair of branches. One branch is operatively connected to one of the cylinder units and another branch is connected to another of the cylinder units. The connector leg is generally parallel to the axis of the crankshaft. The intake manifold may further include a baffle assembly, which directs gas flow within the intake manifold.

Abstract: An exhaust valve assembly for a two stroke internal combustion engine having a cylinder with at least one main exhaust port and one auxiliary exhaust port is disclosed. The assembly comprises a main exhaust valve for at least partially closing the main exhaust port, an auxiliary exhaust valve for at least partially closing the auxiliary exhaust port, the auxiliary exhaust valve being separate from the main exhaust valve, and an actuator for actuation of the main exhaust valve and the auxiliary exhaust valve, wherein the actuator is connected to the main exhaust valve and the auxiliary exhaust valve is connected to the actuator by the main exhaust valve.

Abstract: An air intake system for an internal combustion engine has at least one air box and a short duct for each cylinder. Each duct can be extended to provide higher torque at low speed. At high speed, the shorter duct length can be selectively provided for enhanced engine performance.

Abstract: A drive assembly for a vehicle having at least one wheel and an engine is disclosed. The drive assembly transfers a driving force from the engine to the at least one wheel. The drive assembly includes a rotatable input drive shaft. The input drive shaft is operatively coupled to the engine. The drive assembly further includes a rotatable output drive shaft. The output drive shaft is operatively coupled to the at least one wheel. A first transmission operatively connects the input and output drive shafts. An overload clutch is operatively disposed between the input drive shaft and the first transmission to transfer a driving force from the input drive shaft to the first transmission. The overload clutch may be at least partially mounted to input drive shaft.

Abstract: A personal watercraft is disclosed with a hull, a seating assembly, and a four stroke internal combustion engine below the seating assembly. The engine has at least one intake valve for each of the combustion cylinder chambers, at least one exhaust valve for each of the combustion cylinder chambers, and a valve actuation assembly located in a cylinder head for operating the intake and exhaust valves. At least one air intake passageway is operatively coupled to the combustion cylinder chambers through the intake valves. An air intake manifold is connected to the cylinder head and operatively connected to the at least one air intake passageway. The engine also has a supercharger for boosting air to the air intake manifold. The watercraft also includes a propulsion unit, operatively coupled to the crankshaft, which is located on one end of the two ends of the crankcase.

Abstract: A snowmobile with arrangement of a four cycle engine is disclosed providing a relatively low center of gravity for improved handling and maneuverability. The engine comprises a cylinder unit slanted to the back of the snowmobile and an improved packaging of auxiliary components in order to optimize the location of the center of gravity on the snowmobile. The engine has a balancer shaft rotatably coupled to the crankshaft and the balancer shaft axis is positioned above the crankshaft axis.

Abstract: An engine crankshaft includes a split crankshaft journal that includes offset connecting rod journals for two connecting rods. Oil supply systems disposed on opposite axial sides of the crankshaft journal each lubricate a corresponding one of the connecting rod journals. The oil supply systems are either axial or peripheral oil supply systems that do not require oil to be supplied to the crankshaft through the main crankcase bearings. Consequently, the oil supply systems sufficiently lubricate each connecting rod journal without requiring weakening holes or grooves in the main crankcase bearings.

Abstract: A four cycle engine having at least one cylinder unit is disclosed. The engine includes a continuously variable transmission (CVT) connected to the engine on one side of the engine. An air box is also provided that is located on the same side of the engine as the CVT. The engine further includes an intake manifold operatively connected to the air box for connecting the air box to each cylinder unit and a throttle assembly operatively connected to air box and the intake manifold. The intake manifold may have a generally Y-shaped manifold having a connector leg connected to the throttle assembly and a pair of branches. One branch is operatively connected to one of the cylinder units and another branch is connected to another of the cylinder units. The connector leg is generally parallel to the axis of the crankshaft. The intake manifold may further include a baffle assembly, which directs gas flow within the intake manifold.

Abstract: A cooling system and method of cooling an engine are disclosed. The cooling system includes a first closed loop that circulates coolant at a first temperature and a second closed loop that circulates coolant at a second temperature that is different than the first temperature. Such a construction provides two separate cooling temperature circuits for cooling equipment at different cooling temperatures.