DUROMAX XP10000EH-12132017 User Manual page 47

4.
Measure plug gap
Measure the plug gap with a gauge. The gap should be 0.7-0.8
mm (0.028-0.031 in).
5.
Clean and re-gap
If you are re-using the spark plug, use a wire brush to clean
any dirt from around the spark plug base and then re-gap the
spark plug.
6.
Replace spark plug
Screw the spark plug back into its place on the generator
using the spark plug wrench.
7.
Replace spark plug cap
Replace the spark plug cap.
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