Yamaha 6C Owner's Manual page 124

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903022
NOTE:
If a torque-wrench is not available when
you are fitting a spark plug, a good esti-
mate of the correct torque is 1/4 to 1/2 a
turn past finger-tight. Have the spark plug
adjusted to the correct torque as soon as
possible with a torque-wrench.
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When removing or installing a spark plug,
be careful not to damage the insulator. A
damaged insulator could allow external
sparks, which could lead to explosion or
fire.
Spark plug
I.D. mark
B*HS (–10)
BR*HS (–10)
1 Spark plug gap
2 Spark plug I.D. mark (NGK)
q
4-13
GB
Plug-wrench
size
21 mm (13/16")