Honda BF9.9A Owner's Manual page 36

Spark plug service
Recommended spark plug:
BF9.9A: DR-5HS(NGK), Xl6FSRU(NlPPONDENSO)
BF15A: DR-GHS(NGK), X2OFSR-U(NlPPONDENS0)
To ensure proper engine operation, the spark plug must be properly
gapped and free of deposits.
1. Remove the engine cover.
2. Remove the spark plug caps.
3. Use the wrench supplied in the tool kit to remove the spark plugs.
SPARK PLUG WRENCH
4.Visually inspect the spark plugs. Discard the spark plugs if there is
apparentwear, or if the insulators are cracked or chipped. Clean the
spark plugs with a wire brush if they are to be reused.
5. Measure the plug gaps with a feeler gauge.
Correct as necessary by carefully bending the side electrode.
The gaps should be:
0.60-0.70 mm (0.024-0.028 in)
0.00-0.70 mm
(0.024-0.028 in]
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