Honda BF5A Owner's Manual page 32

Spark plug service
Recommended spark plug:
BPR5ES(NGK); W 1 GEPR-U, W 14EPR-UW)
1. Remove the engine cover.
2. Remove the spark plug cap.
3. Use the wrench supplied in the tool kit to remove the spark plug.
4.Visually inspect the spark plug. Discard the spark plug if there is
apparent wear, or if the insulator is cracked or chipped. Clean the spark
plug with a wire brush if it is to be reused.
5. Measure the plug gap with a feeler gauge.
Correct as necessary by carefully bending the side electrode.
The gap should be :
0.70-0.80 mm (0.028-0.031 in)
6.Check that the spark plug washer is in good condition, and thread the
spark plug in by hand to prevent cross-threading.
7.After the spark plug is seated, tighten with a spark plug wrench to
compress the washer.
NOTE:
If installing a new spark plug, tighten l/2 turn after the spark plug seats to
compress the washer. If reinstalling a used spark plug, tighten l/8-1/4
turn after the spark plug seats to compress the washer.
8. Reinstall the engine cover.
1 NOTICE 1
l
The spark plug must be securely tightened. An improperly tightened
plug can become very hot and may cause engine damage.
l
Use only the recommended spark plug or equivalent. A spark plug
which has an improper heat range may cause engine damage.
0.70-0.80 mm
(0.028-0.031 in)