1) Visually inspect the spark plug. Discard the plug if the insulator is cracked or chipped.
2) Remove carbon or other deposits with a stiff wire brush.
3) Measure the plug gap with a wire-type feeler gauge.
If necessary, adjust the gap by bending the side electrode.
4) Make sure the sealing washer is in good condition; replace the plug if necessary.
5) Install the plug fingertight to seat the washer, then tighten with a plug wrench (an additional 1/2 turn if a new plug) to compress the sealing washer,. If you are reusing a plug, tighten 1/8 – 1/4 turn after the
plug seats.
