The best way to adjust the idle on your Honda OHV lawn mower is with a single cylinder handheld tachometer. There are two adjustments for the idle on the Honda mower. When you use a tachometer to adjust the throttle stop screw, you will ensure that you have enough RPMs to maintain idle and still have fuel efficiency. Tachometers are available at auto parts stores and home improvement centers.
Place the Honda mower outside on level ground. Locate the throttle stop screw and the pilot screw. The throttle stop screw is directly under the air cleaner assembly on the carburetor. The pilot screw is a flathead screw located to the lower left of the pilot screw.
Start your Honda mower and allow the engine to reach operating temperature. The engine will need to run approximately two minutes to warm up.
Place the throttle lever to the low setting. The low setting will have a picture of a turtle on the indicator plate by the handle. Attach the wire from your tachometer to the spark plug wire.
Turn the pilot screw with a flathead screwdriver until the engine will idle without shutting off. The engine should maintain a steady speed while idling.
Turn the throttle stop screw with a Phillips-head screwdriver until the the engine reaches the standard idle speed of 150 RPMs. Turn the throttle stop screw in small increments until the tachometer reads 150 RPMs.