Yamaha Raptor 90 2017 Owner's Manual page 85

1. Spark plug wrench
To check the spark plug
1. Check that the porcelain insulator around the
center electrode of the spark plug is a medi-
um-to-light tan (the ideal color when the ATV
is ridden normally).
TIP
If the spark plug shows a distinctly different color,
the engine could be operating improperly. Do not
attempt to diagnose such problems yourself. In-
stead, have a Yamaha dealer check the ATV.
2. Check the spark plug for electrode erosion
1
Specified spark plug:
3. Measure the spark plug gap with a wire thick-
1. Spark plug gap
Spark plug gap:
8-10
and excessive carbon or other deposits, and
replace it if necessary.
NGK/CR6HSA
ness gauge and, if necessary, adjust the gap
to specification.
0.6–0.7 mm (0.024–0.028 in)
8