Yamaha KODIAK ULTRAMATIC YFM400FWAN 2000 Owner's Manual page 135

1. Spark plug wrench
Inspection
The spark plug is an important engine
component and is easy to inspect. The
condition of the spark plug can indicate the
condition of the engine.
The ideal color on the white insulator
around the center electrode is a medium-
to-light tan color for a ATV that is being rid-
den normally.
Do not attempt to diagnose such problems
yourself. Instead, take the ATV to a
Yamaha dealer. You should periodically
remove and inspect the spark plug be-
cause heat and deposits will cause the
spark plug to slowly break down and
erode. If electrode erosion becomes exces-
sive, or if carbon and other deposits are ex-
cessive, you should replace the spark plug
with the specified plug.
Specified spark plug:
DR8EA (NGK)
Installation
1. Measure the electrode gap with a wire
thickness gauge and, if necessary, ad-
just the gap to specification.
Spark plug gap:
0.6 ~ 0.7 mm (0.02 ~ 0.03 in)
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