Abstract: A breather device disposed in a timing-gear chamber of an engine includes an oil separator rotatable with a camshaft, and a tubular breather housing that removes the oil mist by working in cooperation with the oil separator. The oil separator has a plurality of fins arranged annularly around an axis line of the camshaft at fixed intervals. The tubular breather housing has openings in a periphery wall thereof and surrounds the oil separator.

Abstract: Cooling efficiency of cooling air is enhanced and durability of a continuously variable transmission is improved. The continuously variable transmission to be mounted on a vehicle has a transmission case. A primary pulley driven by an engine and a primary pulley linked to drive wheels are rotatably accommodated in the transmission case. A V-belt is provided to extend for winging between the primary pulley and the secondary pulley, and the rotation of the primary pulley is continuously changed and transmitted to the secondary pulley. Fan blades are formed in the primary pulley, and a scroll surface is formed in transmission case from an intake region of the cooling air toward a discharge region thereof so as to gradually away from top faces of the fan blades in a radial-outer direction. Thereby, blowing efficiency of the cooling air can be enhanced and an interior of the transmission case can be sufficiently cooled, whereby the durability of the V-belt can be enhanced.

Abstract: A breather device disposed in a timing-gear chamber of an engine includes an oil separator rotatable with a camshaft, and a tubular breather housing that removes the oil mist by working in cooperation with the oil separator. The oil separator has a plurality of fins arranged annularly around an axis line of the camshaft at fixed intervals. The tubular breather housing has openings in a periphery wall thereof and surrounds the oil separator.

Abstract: An oil cooling system of an air-cooled engine for cooling the oil reserved in a crankcase of the engine comprises a base plate assembled to the crankcase, an overlapping plate assembled to the base plate; an oil filter supported in the overlapping plate; and radiation fins formed on the base plate and the overlapping plate, wherein the base plate includes an inlet port for receiving the engine oil discharged from an oil pump of the engine, an outlet groove for outputting the engine oil and a first passage groove connecting the inlet port and the outlet groove, the overlapping plate includes an inlet groove opposed to the inlet port, an outlet port opposed to the outlet groove and a second passage groove opposed to the first passage groove to form an oil passage together with the first passage groove, and the base plate and the overlapping plate having through-holes where the filter outlet of the oil filter passes through for the connection with the crankcase.

Abstract: The power transmission system of an engine is mounted on the all-terrain vehicle and has a crankshaft driven by the engine and the crankshaft is arranged in a direction of width of a vehicle body. A sub-shaft is arranged parallel to the crankshaft and the rotation of the crankshaft is transmitted to the sub-shaft via gears. A primary shaft is concentrically mounted on the sub-shaft and is provided with a primary pulley having a variable groove width. A secondary pulley coupled to the primary pulley via a V-belt and having a variable groove width. The rotation of the crankshaft is transmitted to the primary shaft via the sub-shaft arranged parallel to the crankshaft.

Abstract: An oil cooling system of an air-cooled engine for cooling the oil reserved in a crankcase of the engine comprises a base plate assembled to the crankcase, an overlapping plate assembled to the base plate; an oil filter supported in the overlapping plate; and radiation fins formed on the base plate and the overlapping plate, wherein the base plate includes an inlet port for receiving the engine oil discharged from an oil pump of the engine, an outlet groove for outputting the engine oil and a first passage groove connecting the inlet port and the outlet groove, the overlapping plate includes an inlet groove opposed to the inlet port, an outlet port opposed to the outlet groove and a second passage groove opposed to the first passage groove to form an oil passage together with the first passage groove, and the base plate and the overlapping plate having through-holes where the filter outlet of the oil filter passes through for the connection with the crankcase.

Abstract: The power transmission system for the vehicle of the present invention comprises a transmission having an input shaft and an output shaft, the input shaft being operatively connected to an engine, a counter shaft provided in parallel with the output shaft of the transmission, a forward gear train provided between the output shaft of the transmission and the counter shaft and a final reduction gear train provided between the counter shaft and an axle, the axle being operatively connected to the driving wheel. The forward gear train includes a gear having a disk portion mounted on the shaft and a circular gear portion fitted on an external circumference of the disk portion.

Abstract: A power transmission system has a crankshaft mounted rotatably on case and a primary shaft. A clutch drum of the centrifugal clutch is fixed to an inside end of the primary shaft. An inside end of the primary shaft is supported by a bearing for a first transmission, and an outside end of the primary shaft is supported by a bearing for a second transmission in case both of them. The primary shaft is rotatably supported by the outside end and the inside end fixing the clutch drum in the case. Thereby, assembling performance into which the primary shaft and the crankshaft of continuously variable transmission are coupled the crankshaft via the centrifugal clutch is enhanced.

Abstract: An intake port for guiding new intake air into a combustion chamber of a cylinder and an exhaust port for discharging exhaust combustion gas from the combustion chamber to the outside, are formed in a cylinder head mounted on the cylinder for housing a piston movably in a reciprocating manner. The intake port is opened/closed by intake valve, and the exhaust port is opened/closed by exhaust valve. Openings of the intake and exhaust ports at the combustion chamber side are formed to be displaced toward central portion of the combustion chamber.

Abstract: The power transmission system of an engine is mounted on an all-terrain vehicle and has a crankshaft driven by the engine and the crankshaft is arranged in such a way as to extend in a direction of width of a vehicle body. The rotation of the crankshaft is transmitted to a primary shaft via a centrifugal clutch. The primary shaft is provided with a primary pulley having a variable groove width and a secondary shaft is provided with a secondary pulley coupled to the primary pulley via a V belt and having a variable groove width. The rotation of the secondary shaft is transmitted to an output shaft via a forward/backward switching mechanism. The output shaft transmits engine power to an axle which is arranged parallel to the output shaft and is coupled to the driving wheels via gears.

Abstract: Cooling efficiency of cooling air is enhanced and durability of a continuously variable transmission is improved. The continuously variable transmission to be mounted on a vehicle has a transmission case. A primary pulley driven by an engine and a primary pulley linked to drive wheels are rotatably accommodated in the transmission case. A V-belt is provided to extend for winging between the primary pulley and the secondary pulley, and the rotation of the primary pulley is continuously changed and transmitted to the secondary pulley. Fan blades are formed in the primary pulley, and a scroll surface is formed in transmission case from an intake region of the cooling air toward a discharge region thereof so as to gradually away from top faces of the fan blades in a radial-outer direction. Thereby, blowing efficiency of the cooling air can be enhanced and an interior of the transmission case can be sufficiently cooled, whereby the durability of the V-belt can be enhanced.

Abstract: The power transmission system of an engine is mounted on an all-terrain vehicle and has a crankshaft driven by the engine and the crankshaft is arranged in such a way as to extend in a direction of width of a vehicle body. The rotation of the crankshaft is transmitted to a primary shaft via a centrifugal clutch. The primary shaft is provided with a primary pulley having a variable groove width and a secondary shaft is provided with a secondary pulley coupled to the primary pulley via a V belt and having a variable groove width. The rotation of the secondary shaft is transmitted to an output shaft via a forward/backward switching mechanism. The output shaft transmits engine power to an axle which is arranged parallel to the output shaft and is coupled to the driving wheels via gears.

Abstract: There is provided an engine controller that prevents the engine operation from being continued due to a throttle valve recovery failure. When a throttle lever is in the unoperated state and the engine revolution higher than a set revolution has remained for a set duration, the engine controller decides that the recovery failure of a throttle valve has occurred and performs a control to stop the operation of the engine. This prevents the engine operation from being continued against the will of the operator in the event that the throttle valve fails to recover. When the engine is used as a motor of a vehicle, for example, the running of the vehicle can be stopped, thus assuring a higher safety.

Abstract: A first fuel injection pulse width is provided based on engine operating conditions. The amount of fuel is necessary for one combustion stroke of the engine at one time. A second fuel injection pulse width is provided based on engine operating conditions so as to inject at one time an amount of fuel for two combustion strokes of the engine. The first fuel injection pulse width is compared with a minimum value. The first fuel injection pulse width is selected when the first fuel injection pulse width is larger than the minimum value, and otherwise, the second fuel injection pulse width is selected when the first fuel injection pulse width is smaller than the minimum value. Fuel is injected at the selected injection pulse.

Abstract: An engine has a water pump and a recoil starter. A recoil starter housing secured to the engine has a boss coaxial with a crankshaft of the engine. An impeller shaft of the water pump is connected to an end of the crankshaft, and is rotatably mounted on the boss of the recoil starter housing. The recoil starter is rotatably mounted on the boss of the housing.

Abstract: A snowmobile has an upper hood having a plurality of air intakes, an engine provided downstream of the air intakes, and an air box having an air cleaner and communicating with an inlet port of the engine. An electronic control unit is disposed in a case which is secured to an upper wall of the air box. A deflector is disposed between the air intakes and the case so as to deflect intake air from the case.

Abstract: An idling speed adjustment system for an engine, in which a pulse width for corrected fuel injection in the idling operation of the engine is set by adjusting idling adjustment means adapted to be adjusted from outside the system. Subsequently, a pulse width for fuel injection in the idling operation is determined in such a way that a pulse width for basic fuel injection which is set on the basis of a throttle opening degree and engine speed is corrected with several correction values which are set on the basis of detected engine state parameters, and the idling-operation corrected fuel injection pulse width which is set as described above.

Abstract: An ignition device intermittently produces an ignition voltage in synchronism with speed of an engine. A fuel injection control is provided for operating a fuel injector for injecting fuel. A fuel pump for supplying fuel to the fuel injector is stopped at a time after the ignition and fuel injection stop, thereby keeping fuel pressure in a fuel supply passage.

Abstract: A motor vehicle has a continuously variable belt-drive transmission having a clutch means which engages when speed of an engine is higher than a clutch engaging speed. A plurality of basic pulse widths for injecting fuel are stored in a memory arranged in accordance with the engine speed and opening degree of a throttle valve. Some of the basic pulse widths in a speed range lower than the clutch engaging engine speed are increased for acceleration of the engine. One of the basic pulse widths is retrieved in accordance with the actual engine speed and the throttle valve opening degree, and a fuel injection pulse width is calculated based on the retrieved basic pulse width.

Abstract: A crankcase temperature sensor is provided for detecting temperature of a crankcase. A low speed basic injection pulse width is provided based on the detected crankcase temperature for low engine speed. An ordinary fuel injection pulse width is provided in accordance with engine operating conditions for ordinary engine operating condition. A comparator is provided for comparing the low speed injection pulse width and the ordinary fuel injection pulse width with each other. A larger injection pulse width is determined for injecting fuel.