Yamaha RAPTOR YFM660RP Owner's Manual page 125

Installation
1. Measure the electrode gap with a wire
thickness gauge and, if necessary, adjust
the gap to specification.
Spark plug gap:
0.8 ~ 0.9 mm (0.03 ~ 0.04 in)
a. Spark plug gap
2. Clean the gasket surface. Wipe off any
grime from the threads.
3. Install the spark plug and tighten it to the
specified torque.
Tightening torque:
Spark plug:
17.5 Nm (1.75 m·kgf, 12.7 ft·lb)
NOTE:
_
If a torque wrench is not available when you
are installing a spark plug, a good estimate of
the correct torque is 1/4 to 1/2 turn past finger
tight. Have the spark plug tightened to the
specified torque as soon as possible.
_
4. Install the spark plug cap.
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