Application of a Simple Mechanical Phasing Mechanism for Independent Adjustment of Valves in a Pushrod Engine

A dual independent valve phasing mechanism is applied to an air-cooled, pushrod actuated, V-twin motorcycle engine with two cams. As described, the mechanism is manually adjusted. The design is readily adapted to automated control.

The phasing concept mounts the roller lifter in an eccentric sleeve. Rotation of the sleeve advances or retards the position of the roller lifter relative to the cam lobe. This action in turn advances or retards valve timing. Valve lift and duration are essentially unaffected.

Predicted and experimental results from varying valve phase under idle, part load, and full load conditions are presented. The effect of valve overlap on hydrocarbon emissions at idle and NOx emissions at part load are described. Changes in volumetric efficiency and torque at wide-open throttle operation are also described.