Abstract: A cooling system adapted for a liquid-cooled type of two-cycle multicylinder engine. The thick-walled portion of a crank case between adjacent cylinders is provided with a cooling-liquid passage. The delivery port of a liquid pump is fixedly secured to one end of the cooling-water passage at the intake side of the cylinder, while the other end of the passge at the exhaust side of the cylinders is flow connected to liquid jackets in the cylinder blocks.

Abstract: An actuation device for a tachometer adapted to transmit the revolutions of an engine crankshaft to the tachometer, wherein the oil pump of the engine is utilized as a speed reducing mechanism for transmitting the revolutions of the engine crankshaft to the tachometer after the engine speed is reduced. A cable connected at one end to the plunger of the oil pump whose speed is reduced by means of a gearing is connected at the other end to the tachometer. Thus, by utilizing the oil pump, it is possible to transmit the revolutions of the engine crankshaft to the tachometer without requiring a speed reducing mechanism provided exclusively for the tachometer.

Abstract: An air cleaner for an engine of a snow mobile provided with an endless vehicle track driven by the engine, includes an air cleaner main body comprising a duct extending longitudinally of the snow mobile and disposed on a floor covering of the endless vehicle track. The air cleaner main body is connected at its forward end to a carburetor for the engine and includes a rearward portion formed with a plurality of air inlet apertures. A riders' seat is mounted on the rear portion of the air cleaner main body and includes a shock-absorbing member for enclosing the air inlet apertures and an outer cover member for covering the shock-absorbing member. The shock-absorbing member serves concurrently as a cleaning element of the air cleaner, and at least one air intake port is formed in the outer cover of the seat at its rear end or one or both of its sides. The air cleaner main body is formed with an increased volume section which serves as a muffler for silencing engine intake noises.

Abstract: Twin cylinder two cycle engine including a pair of stepped cylinders and a pair of stepped pistons slidable in said cylinders defining annular spaces of variable volume in said cylinders. The pistons are interconnected each other with 180.degree. phase difference. Air-fuel mixture introduced into the annular space in one cylinder is forced into the crankchamber of the other cylinder during the upward stroke of the associated piston, so that an additional charge is provided.

Abstract: An integrated fuel supply unit 10 includes a filter 18, a spring biased supply valve 21 operated by a valve diaphragm 22, and a pump chamber 38. Fuel enters and leaves the pump chamber through non-return flap valves 37, 39 incorporated in the diaphragm 22, and the latter is deflected to open the supply valve by a chamber 29, 29' pressurized through a non-return bleed valve 30, 30' by the pulsating engine crankcase pressure, which also operates (reciprocates) the fuel pump diaphragm.

Abstract: An internal combustion engine comprising a crankshaft mounted in a crankcase and connected with a piston through a connecting rod, an accessory drive shaft connected at one end with the crankshaft and support at the same end by the crankcase, a water pump including a rotatable element connected with the other end of the accessory drive shaft and a casing having an outlet port connected with a co-operating passage in the crankcase, said casing being secured to the crankcase at the outlet port portion so as to provide a rigid support for the drive shaft.

Abstract: Two stroke engines of crankcase precompression type comprising an integral main body block which includes a cylinder block section and a crankcase upper section, and to which a crankcase lower section and a cylinder head are secured at the lower and upper ends thereof. The body block is formed with scavenging passages of which lower ends are substantially straight so as to facilitate removal of the block from manufacturing dies. The engine includes a crankshaft which is supported by bearings secured to the crankcase lower section by means of separate semi-circular retaining members.

Abstract: Air-cooled two stroke internal combustion engine having a cooling air blower driven by the engine and a lubricating oil pump for supplying lubricating oil to the engine, said lubricating oil pump being housed in the hub portion of the blower.

Abstract: A rotary engine wherein a side port is formed in one side housing, and a main peripheral port, communicating with the side port, and a bypass peripheral port, communicating with a bypass passage formed in another side housing, are formed in a rotor housing, the side port being maintained in communication with the carburetor through a passage formed in the rotor, while the bypass peripheral port communicates with the carburetor by bypassing the passage in the rotor. Respective valves are mounted in the main peripheral port and the bypass peripheral port, and the two valves are closed or throttled at low engine speeds. The bypass peripheral port opens at higher engine speeds than the main peripheral port.