Kohler is a small engine manufacturer whose engines are commonly found on lawn tractors and other larger lawn & garden equipment. For instance, many Cub Cadet lawn tractors are powered by Kohler engines. These engines have a governor that is connected to the throttle to keep the engine running smoothly under varied workloads. If the engine revs up and down or the power drops substantially when under a workload, you may need to repair a governor on a Kohler engine.
Disconnect the spark plug wire from the spark plug by pulling on the black rubber boot that covers the tip of the spark plug.
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Loosen the screws and remove the air filter from the carburetor with a screwdriver.
Locate the throttle fly mechanism on the top of the carburetor. It should have a linkage spring that stretches horizontally to the L-shaped governor arm.
Loosen the nut on the bottom of the L-shaped governor arm about one full turn with an open end wrench to loosen the governor arm from the governor cross shaft.
Grasp the cross shaft just beneath the governor arm with a pair of needlenose pliers, and rotate the cross shaft counter-clockwise as far as it will turn. When it stops, hold it in place and pull back on the governor arm as far as it will go. Hold the two in place, and tighten the nut on the bottom of the governor arm (which you loosened in the previous step) with an open-end wrench.
Replace the air filter. Reconnect the spark plug wire to the spark plug. Start the engine. Allow it to warm up for about five minutes.
Test the engine under various workloads. If the engine still revs or has a power drop, turn off the engine, and remove the air filter once again.
Locate the linkage spring between the throttle and the governor arm. The governor arm will have a series of holes for the linkage spring. Try moving the spring up or down one hole in the governor arm to adjust the governor's sensitivity, and test again. Continue testing and moving the linkage between holes in the governor arm until you have found the smoothest setting. If none of the hole locations seem to improve the problems, your Kohler engine's governor may have some more serious problems with internal parts, and should be looked at by a qualified Kohler technician.