Yamaha VX250A, Owner'S Manual

Page: 76 / 118

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4-11
EMU01202
CLEANING AND ADJUSTING SPARK
PLUG
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When removing or installing a spark
plug, be careful not to damage the insu-
lator. A damaged insulator could allow
external sparks, which could lead to
explosion or fire.
The spark plug is an important engine com-
ponent and is easy to inspect. The condition
of the spark plug can indicate something
about the condition of the engine. For
example, if the center electrode porcelain is
very white, this could indicate an intake air
leak or carburetion problem in that cylinder.
Do not attempt to diagnose any problems
yourself. Instead, take the outboard motor
to a Yamaha dealer. You should periodical-
ly remove and inspect the spark plug
because heat and deposits will cause the
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
another of the correct type.
Before fitting the spark plug, measure the
electrode gap with a wire thickness gauge;
adjust the gap to specification if necessary.
Standard spark plug:
Refer to “SPECIFICATIONS”, page 4-1.
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