Briggs & Stratton engines are used in a variety of lawn and garden equipment. The governors installed in these engines are designed to prevent the engines from operating at speeds beyond their capabilities. Additionally, the governors help keep the engines running at optimum speeds for the workloads they need to handle; much like a cruise control system, a Briggs & Stratton governor will open or close the throttle of engine, as needed.
Disconnect the spark plug wire from the spark plug by pulling on the rubber boot at the tip of the spark plug.
Inspect the governor arm and governor spring on the side of the engine. The governor arm should move freely, particularly when you move the throttle lever on the carburettor in a back-and-forth motion. If the governor spring appears to be stretched beyond normal, replace it with a new governor spring.
Loosen the nut at the base of the governor arm with a socket, so that the governor arm swings freely.
Push the throttle linkage so that the throttle is wide open. Notice the direction in which the governor moves when following the throttle linkage.
Hold the throttle linkage wide open and move the governor arm as far as it will go in the direction it travelled in the previous step. Tighten the nut at the base of the governor arm.
Release the throttle linkage and move the governor arm back and forth, checking to see that the throttle linkage moves freely.
Reconnect the spark plug wire to the spark plug, then start the engine. Adjust the speed of the throttle to put the engine under different loads; as you do this, listen to make sure that the engine runs smoothly at all speeds.