Abstract: An internal combustion engine having a vacuum release mechanism that includes a centrifugally actuated member movably attached to the camshaft and having a vacuum release cam extending therefrom. The vacuum release cam is in lifting engagement with the exhaust valve assembly at crankshaft cranking speeds during a portion of the power stroke to relieve vacuum forces opposing motion of the piston. The vacuum release cam centrifugally pivots out of engagement with the exhaust valve assembly in response to the crankshaft attaining running speeds.

Abstract: A compression release mechanism for an internal combustion engine wherein a rotatable pin positioned axially parallel to the camshaft is rotatably received in the cams, and has a lift member mounted at an axial end thereof. The pin is non-cylindrically shaped at one axial end thereof, and the non-cylindrically shaped end is received and secured into a correspondingly shaped bore disposed in a cylindrical hub extending perpendicularly from a one-piece flyweight. An optional adhesive can be used to secure the pin to the hub of the flyweight. According to a further optional embodiment, the hub can be crimped so as to engage the release pin. The disclosed configuration ensures a secure engagement and therefore avoids slipping between the release pin and the flyweight. Further, the design facilitates easy alignment of the pin with the flyweight during assembly. The flyweight can be a one-piece integral structure.

Abstract: An oil drain valve and oil sight gauge assembly for an internal combustion engine of an implement such as a lawnmower. The oil drain valve includes a valve member disposed in a valve body attached to the engine housing and disposed above the mower deck. The valve member may be selectively moved to allow oil to drain from an oil sump in the engine crankcase through a drain opening disposed below the mower deck. The valve member is retained in the valve body when the oil drain valve is opened to prevent the valve member from being lost. The oil sight gauge is internally vented to the crankcase to provide an accurate indication of the oil level in the crankcase, and is visually associated with the oil drain valve to provide an operator with a visual confirmation that all of the oil has been drained from the crankcase.

Abstract: An internal combustion engine having a vacuum release mechanism that includes a centrifugally actuated member movably attached to the camshaft and having a vacuum release cam extending therefrom. The vacuum release cam is in lifting engagement with the exhaust valve assembly at crankshaft cranking speeds during a portion of the power stroke to relieve vacuum forces opposing motion of the piston. The vacuum release cam centrifugally pivots out of engagement with the exhaust valve assembly in response to the crankshaft attaining running speeds.