7
PERIODIC MAINTENANCE AND ADJUSTMENT
7-9
1. Spark plug gap
Checking the spark plugs
The spark plugs are important engine
components, which should be checked
periodically, preferably by a Yamaha
dealer. Since heat and deposits will
cause any spark plug to slowly erode,
they should be removed and checked
in accordance with the periodic
maintenance and lubrication chart. 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 medium-to-light tan (the
ideal color when the vehicle is ridden
normally), and all spark plugs installed
in the engine should have the same
color. If any spark plug shows a
distinctly different color, the engine
could be operating 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 erosion
and excessive carbon or other
deposits, it should be replaced.
Specified spark plug:
NGK/CR9E
Before installing a spark plug, the
spark plug gap should be measured
with a wire thickness gauge and, if
necessary, adjusted to specification.
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)
Clean the surface of the spark plug
gasket and its mating surface, and
then wipe off any grime from the
sparkplug threads.
Tightening torque:
Spark plug:
13 Nm (1.3 m·kgf, 9.4 ft·lbf)
TIP
If a torque wrench is not available
when installing a spark plug, a good
estimate of the correct torque is
1/4–1/2 turn past finger tight.
However, the spark plug should be
tightened to the specified torque as
soon as possible.
