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EBU00287
Spark plug inspection
The spark plugs are important engine compo-
nents and are easy to inspect. The condition
of the spark plugs can indicate the condition
of the engine.
Normally, all spark plugs from the same engine
should have the same color on the white porce-
lain insulator around the center electrode. The
ideal color at this point is a medium to light tan
color for a machine that is being ridden normal-
ly. If one spark plug shows a distinctly different
color, there could be something wrong with the
engine.
Do not attempt to diagnose such problems your-
self. Instead, take the machine to a Yamaha deal-
er. You should periodically remove and inspect
the spark plugs because heat and deposits will
cause any spark plug to slowly break down and
erode. If electrode erosion becomes excessive, or
if carbon and other deposits are excessive, you
should replace the spark plug with the specified
plug.
Before installing a spark plug, measure the
electrode gap with a feeler gauge and adjust
to specification.
a. Spark plug gap
Standard spark plug:
BR8ES (NGK)
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)
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