How do you adjust a carburetor on a lawn mower?

The following procedure applies to all small engines

If the engine does not start:

(1) rotate the carburetor main jet needle valve clockwise (close) until it touches its stopping point - DO NOT FORCE OR GO BEYOND THE POINT OF TOUCHING as it may damage the tip.

(2) Rotate the needle valve counter-clockwise (open) 1-1/4 to 1-1/2 turns - this should be close enough to start the engine. Start the engine and let it warm up about five minutes.

(3) Rotate the needle valve clockwise (close) slowly until the engine starts to stall for lack of fuel, then rotate the needle valve counter-clockwise (open) slowly until the engine starts to stall from flooding (too much fuel).

(4) Set the needle valve to a midpoint between the two extremes for the best "purr" of the engine. If the engine "sputters" when a load is added, open the needle valve an extra 1/8 turn for a slightly richer mixture.

If the engine starts and you just want to adjust the carburetor, steps (1) and (2) are not necessary.