Abstract: An internal combustion engine with valve rest mechanisms. Exhaust secondary air is introduced at an exhaust port in a stable manner regardless of the resting, opening and closing operations of exhaust valves. Certain exhaust valves in the internal combustion engine are equipped with valve rest mechanisms. Exhaust valves that are not equipped with valve rest mechanisms located on neighboring cylinders are located on neighboring sides of their respective cylinders.

Abstract: A water pump includes a pump body and a pump cover. An impeller is housed in a pump chamber defined by the pump body and pump cover. The impeller is attached to one end of a hollow pump shaft. The pump shaft is engaged with a driving section at its other end. An intermediate part of the pump shaft is supported by a shaft support section, in the form of a cylindrical section, of the pump body. The shaft support section is longer than a diameter of the pump shaft. The shaft support section is lubricated via an oil groove. One end of the shaft support section is brought into contact with a flange of the pump shaft via a washer. The flange is integrally formed on the pump shaft by a beading process.

Abstract: A lubricating oil feeding apparatus of an internal combustion engine can adjust an amount of oil fed to each bearing and provides for a reduced number of parts for a shaft portion structure of a starter driven gear. In the engine, a balancer shaft is synchronously rotated with a crankshaft. The crankshaft and the balancer shaft are rotatably supported on a split surface of a crankcase by plain bearings. Parallel oil passages communicate with oil holes provided in the plain bearings for exclusively feeding lubricating oil to at least the crankshaft and the balancer shaft. The opening areas of the oil holes provided in the plain bearings of the balancer shaft are smaller than the oil holes provided in the plain bearings of the crankshaft. An outer portion of a starter one-way clutch can also be integrally fitted on a rotor. A driven gear of the starter is connected to a starter drive gear of a starter motor by intermediate gears. The diameter D.sub.

Abstract: A chain guide structure having, in combination, a chain cover and a chain guide member which can easily and securely be placed on the chain cover for temporary assembling, and capable of improving the efficiency of the assembling work. A chain guide structure for guiding a chain wound round a driving sprocket supported on the sidewall of a crankcase and covered with a cover attached to the sidewall includes an elastic chain guide member having a substantially semicircular shape opening toward the rear and supported on the inner surface of the cover so as to extend along the chain. At least two ribs are formed on the inner surface of the cover so as to hold the chain guide member by elastically deforming the chain guide member so that the width of the open end of the chain guide member is changed.

Abstract: This invention is concerned with an improved system of dynamic balancing of the primary and secondary vibrations associated with combustion and inertial momentum effects, in particular, in single cylinder engines. By means of the primary and secondary balancing shafts, the invention achieves maximum balancing effects in small spaces, by combining the power transmission and dynamic balancing functions of the shafts; by mechanical arrangement of the primary and secondary balancing shafts in the vicinity of and parallel with the crank shaft; and by a judicious choice of the inter-shaft distances to permit placing the largest possible momentum balancing weights to the balancing sections.

Abstract: An engine employing multiple valves which are mutually inclined. A valve actuating assembly includes two camshafts. Primary rocker arms are driven by the camshafts and in turn drive secondary rocker arms. The secondary rocker arms are pivotally mounted about common shafts and extend to the valves. The common shafts are located between the valves.