Engine start device of a rotary valve carburetor

Abstract

A compact engine start device of a combustion engine rotary-type carburetor overrides normal operation of a rotary throttle valve to provide a richer mixture of fuel-and-air to start a cold engine. Rotation of a start lever of the start device activates a releasable camming interface coupler causing the throttle lever to rotate about a rotary axis and axially lift partially out of the carburetor at prescribed angular and axial distances. This provides the engine, through a fuel-and-air mixing passage, with a controlled and enriched ratio and volume of a fuel-and-air mixture. Preferably, the start lever has a projecting rod that inserts into a hole in the carburetor body for rotation about an axis orientated substantially parallel to the rotary axis. An outward surface of the start lever is in rotational sliding contact with a low-profile, preferably cantilevered, retention arm preferably formed unitarily to a metering fuel pump cover engaged removably to the body of the carburetor, thus allowing rotational movement but preventing axial movement of the start lever. Because the start lever does not move axially to displace the rotary throttle valve, the height of the start lever is favorably minimized. Moreover, the start lever preferably has a knob for user interface at a distal end of the lever that conforms generally about the retention arm thus maximizing knob size yet not contributing to an increase in carburetor size.