Yamaha GRIZZLY 450 YFM450DF Owner's Manual page 107

3. Remove the spark plug as shown, with the
spark plug wrench included in the owner's
tool kit.
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
and excessive carbon or other deposits, and
replace it if necessary.
Specified spark plug:
NGK/DR8EA
3. Measure the spark plug gap with a wire thick-
ness gauge and, if necessary, adjust the gap
to specification.
8-15
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