Honda EM650 Owner's Manual page 31

4. Visually inspect the spark plug. Discard it 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: 0.6-0.7 mm (0.024-0.028 in)
0.6 - 0.7 mm (0.024-0.028 in)
6. Check that the spark plug washer is in good condition, and thread the spark
plug in by hand to prevent cross-threading.
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