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EBU35121
Checking the spark plugs
The spark plug is an important engine com-
ponent which should be periodically
checked, preferably by a Yamaha dealer.
Since heat and deposits will cause any spark
plug to slowly erode, the spark plugs should
be removed and checked in accordance with
the periodic maintenance chart for the emis-
sion control system. In addition, the condition
of the spark plugs can reveal the condition of
the engine.
The porcelain insulator around the center
electrode of each spark plug should be a me-
dium-to-light tan color (the ideal color when
the vehicle is ridden normally), and all spark
plugs installed in the engine should have a
similar color. If any spark plug shows a dis-
tinctly different color, the engine could be op-
erating improperly. Do not attempt to
diagnose such problems yourself. Instead,
have a Yamaha dealer check the vehicle.
If a spark plug shows signs of electrode ero-
sion and excessive carbon or other deposits,
it should be replaced.
Before installing a spark plug, the spark plug
gap should be measured with a wire thick-
ness gauge and, if necessary, adjusted to
specification.
Specified spark plug:
NGK/LMAR8GI-8
1. Spark plug gap
1
UB4M11E0.book Page 32 Tuesday, August 4, 2020 1:04 PM
