Honda HS520A Owner's Manual page 28

SERVICING YOUR SNOWTHROWER
2. Inspect the spark plug. Replace it if the electrodes are worn or if
the insulator is cracked, chipped, or fouled with deposits. Make
sure that the spark plug washer is in good condition.
NOTICE
Use only the recommended spark plugs or equivalent. Spark plugs
which have an improper heat range may cause engine damage.
A replacement spark plug may be purchased from a servicing
Honda snowthrower dealer. See page 49 for a part number list.
SPARK PLUG: BPR5ES (NGK) or W16EPR-U (DENSO)
3. Measure the plug gap with a feeler
gauge. Correct as necessary by
bending the side electrode.
PLUG GAP: 0.028 ~ 0.031 inch
(0.70 ~ 0.80 mm)
4. Thread the spark plug in by hand to
prevent cross-threading.
5. After the spark plug is seated,
tighten with a spark plug wrench to compress the washer.
If installing a new spark plug, tighten 1/2 turn after the spark plug
seats to compress the washer. If reinstalling a used spark plug,
tighten 1/8 to 1/4 turn after the spark plug seats.
NOTICE
The spark plug must be securely tightened. An improperly
tightened spark plug can become hot and may damage the engine.
6. Connect the spark plug cap.
7. Close the spark plug access panel.
26
0.028 ~ 0.031 INCH
(0.70 ~ 0.80 mm)