Honda BF8, BF9.9 and BF10 Outboard Motors Shop Manual., Page 55Get this manual
Remove the spark plug caps, then remove the spark plugs using spark plug wrenchVisually inspect the spark plugDiscard the plug if the insulator is cracked or chippedRemove carbon other deposits with stiff brushMeasure the plug gap with wire-type feeler gaugeIf necessary, adjust the gap bending the side electrodeStandard spark plug Spark plug gap
111 SPARK PLUG WRENCH
CR5EH-9 (NGK) U16FER9 (DENSO)
0.80.9 (0.0310.036 in)
0.80.9 mrn
8Make sure the sealing washers are in good condition; replace if necessary
111 SIDE ELECTRODE
9) Install the plug fingertight seat the washer, then