Honda Power Products WJR2525 Manual De Explicaciones página 61

Spark plug service
Recommended spark plug: CMR4H (NGK)
CAUTION:
Never use a spark plug of incorrect heat range.
To ensure proper engine operation, the spark plug must be properly
gapped and free of deposits.
1. Loosen the 4 mm hex. bolt, then remove the engine top cover.
Do not pull the starter grip and start the engine without the engine
top cover.
There are rotating part and hot parts under the cover.
ENGINE TOP COVER
58
4 mm HEX. BOLT