Honda RS150R 2019 Owner's Manual page 59

10. Make sure the plug washer is in good
condition.
11. Install the spark plug. With the plug
washer attached, thread the spark plug
in by hand to prevent cross-threading.
12. Tighten the spark plug:
●
If the old plug is good:
1/8 turn after it seats
●
If installing a new plug, tighten it twice
to prevent loosening:
a) First, tighten the plug:
NGK: 1/2 turn after it seats.
DENSO: 3/4 turn after it seats.
b) Then loosen the plug.
c) Next, tighten the plug again:
1/8 turn after it seats
NOTICE
An improperly tightened spark plug can damage the
engine. If a plug is too loose, a piston may be damaged.
If a plug is too tight, the threads may be damaged.
Spark Plug
13. Reinstall the spark plug cap. Take care to
avoid pinching any cables or wires.
14. Install the parts in the reverse order of
removal.
u Checking Spark Plug
55