Abstract: A combination of an engine and a pump. An integral first housing section defines a portion of both the engine housing and the pump housing and has a first major surface which defines a portion of the interior engine housing surface and an oppositely disposed second surface which defines a portion of the interior pump housing surface. The first housing section has an opening and a first bearing is disposed therein. The crankshaft extends through the opening and is supported by the first bearing. A pump driving mechanism, such as a wobble plate or camming member, is coupled with the freely extending length of the crankshaft projecting beyond the first bearing. The first major surface may define an oil sump within the engine and an oil passage extending between the first and second major surfaces may communicate oil between the engine and the pump.

Abstract: A combination of an engine and a pump. An integral first housing section defines a portion of both the engine housing and the pump housing and has a first major surface which defines a portion of the interior engine housing surface and an oppositely disposed second surface which defines a portion of the interior pump housing surface. The first housing section has an opening and a first bearing is disposed therein. The crankshaft extends through the opening and is supported by the first bearing. A pump driving mechanism, such as a wobble plate or camming member, is coupled with the freely extending length of the crankshaft projecting beyond the first bearing. The first major surface may define an oil sump within the engine and an oil passage extending between the first and second major surfaces may communicate oil between the engine and the pump.

Abstract: A compression release mechanism for small internal combustion engines, including a compression release member having an auxiliary cam and a weight section. The compression release member is supported for rotation on an annular bearing surface which is in eccentric relation to the longitudinal axis of the engine camshaft. At engine cranking speeds, the compression release member rotates with the camshaft, and the auxiliary cam projects beyond the base circle of a cam lobe on the camshaft to periodically engage a valve to vent pressure from the engine combustion chamber during the compression stroke of the piston to aid in engine cranking. After the engine starts, rapid rotation of the camshaft causes the compression release member to rotate under the inertial load of the weight section thereof to a position in which the auxiliary cam is retracted within the base circle of the cam lobe such that combustion may proceed in a conventional manner.

Abstract: A compression release mechanism for small internal combustion engines, including a compression release member having an auxiliary cam and a weight section. The compression release member is supported for rotation on an annular bearing surface which is in eccentric relation to the longitudinal axis of the engine camshaft. At engine cranking speeds, the compression release member rotates with the camshaft, and the auxiliary cam projects beyond the base circle of a cam lobe on the camshaft to periodically engage a valve to vent pressure from the engine combustion chamber during the compression stroke of the piston to aid in engine cranking. After the engine starts, rapid rotation of the camshaft causes the compression release member to rotate under the inertial load of the weight section thereof to a position in which the auxiliary cam is retracted within the base circle of the cam lobe such that combustion may proceed in a conventional manner.

Abstract: The present invention provides a lubrication system for small internal combustion engines. In a first aspect, a helical oil pump includes a helical insert which is disposed within a bore in the engine camshaft and is rotationally fixed with respect to the crankcase. During running of the engine, rotation of the camshaft draws oil from the oil sump upwardly through the bore in the camshaft and around the helical insert to provide lubrication oil directly to the upper camshaft bearing and to the upper crankshaft bearing. In another aspect, an impeller oil pump includes a pump chamber defined between the camshaft gear and a pump body which is rotationally fixed with respect to the crankcase and in communication with the oil sump. An impeller assembly mounted on the camshaft is disposed within the pump chamber, and draws oil from the oil sump into the pump chamber.

Abstract: A compression release device for a small internal combustion engine, including a flyweight operatively coupled to a cam member via a cam pivot shaft, wherein a lever arm associated with the flyweight is longer than a lever arm associated with the cam member, such that a relatively small component of pivotal movement of the flyweight is translated into a relatively large component of rotation of the cam member. At engine cranking speeds, a spring biases the flyweight to a first position, such that a cam surface of the cam member extends beyond the base circle of the exhaust cam lobe to partially open the exhaust valve and allow release of pressure within the combustion chamber of the engine. At engine running speeds, the flyweight is moved under centrifugal force to a second position, rotating the cam member to a corresponding second position in which the cam surface is disposed within the base circle of the exhaust cam lobe, such that combustion may occur in a conventional manner.

Abstract: An overhead cam engine having a drive train including a crankshaft rotatably disposed within a crankcase and driven by a piston-connecting rod assembly. The crankshaft drives a timing shaft at half the speed of the crankshaft through a gear set within in the crankcase. The timing shaft is parallel to the crankshaft, and has an end extending externally of the crankcase with a timing pulley mounted thereon. The timing pulley is drivingly attached through an external timing belt to a camshaft pulley mounted on an end of a camshaft which extends externally of the cylinder head. The camshaft has a pair of cam lobes mounted thereon inside the cylinder head for actuating intake and exhaust valves within the cylinder head.