Honda ER2500CX Manual De Explicaciones página 47

SERVICING YOUR GENERATOR
5.Make sure that the spark plug sealing washer is in good condition,
and thread the spark plug in by hand to prevent cross threading.
6.After the spark plug seats, tighten with the spark plug wrench to
compress the washer.
If reinstalling a used spark plug, tighten 1/8—1/4 turn after the spark
plug seats.
If installing a new spark plug, tighten 1/2 turn after the spark plug
seats.
A loose spark plug can overheat and damage the engine.
Overtightening the spark plug can damage the threads in the cylinder
head.
7.Attach the spark plug cap.
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