Spark Plug Inspection - Yamaha ZUMA CW50N Owner's Manual

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1. Spark plug gap

Spark plug 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 porcelain insulator
around the center electrode is a me-
dium-to-light tan color for a scooter that
is being ridden normally. Do not attempt
to diagnose any problems yourself.
Instead, take the scooter to a Yamaha
dealer. You should periodically remove
and inspect the spark plug because
heat and deposits will cause the spark
plug to slowly break down and erode.
PERIODIC MAINTENANCE AND MINOR REPAIR
If electrode erosion becomes exces-
sive, or if carbon and other deposits are
excessive, you should replace the
spark plugs with the specified plug.
Standard spark plug:
BR8HS (NGK)
Before installing the spark plug,
measure the electrode gap with a wire
EAH20202
thickness gauge and adjust the gap to
specification as necessary.
Spark plug gap:
0.5 ~ 0.7 mm (0.020 ~ 0.031 in)
When installing the plug, always clean
the gasket surface and use a new
gasket. Wipe off any grime from the
threads and tighten the spark plug to
the specified torque.
Tightening torque:
Spark plug:
20 Nm (2.0 m·kg, 14 ft·lb)
NOTE:
If a torque wrench is not available when
you are installing a spark plug, a good
estimate of the correct torque is 1/4 to
1/2 turn past finger tight. Have the spark
plug torqued to the correct value as
soon as possible with a torque wrench.
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EUU03801
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