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4-7
MAINTENANCE & CARE 4
SPARK PLUG CLEANING AND
ADJUSTMENT
Be careful not to damage the insu-
lator when removing or installing a
spark plug. A damaged insulator
could allow sparks to escape, which
could result in a fire or explosion.
The spark plug is an important engine
component and is easy to inspect. The
condition of the spark plug can indi-
cate something about the condition of
the engine. For example, if one spark
plug has a distinctly different color,
the engine could require servicing. Do
not attempt to diagnose any problems
yourself.
Have a Yamaha dealer service the
boat. Remove and inspect the spark
plugs periodically; heat and deposits
will cause the spark plugs to slowly
break down and erode. If electrode
erosion becomes excessive, or if car-
bon and other deposits are excessive,
replace the spark plug with the speci-
fied plug.
To remove a spark plug:
1) Remove the air filter case cover and
air filter element. (See page 4-11 for
air filter element removal and instal-
lation procedures.)
2) Remove the spark plug cap.
NOTICE: Do not use any tools to
remove or install the spark plug
cap, otherwise the ignition coil
coupler could be damaged. The
spark plug cap may be difficult
to remove because the rubber
seal on the end of the cap fits
tightly. To remove the spark plug
cap, simply twist it back and forth
while pulling it up; to install it,
twist it back and forth while push-
ing it down.
3) Remove the spark plug. Measure
the spark plug gap with a wire thick-
ness gauge. Replace the spark plug
or adjust the gap to specification if
necessary.
To install a spark plug:
1) Clean the gasket surface.
2) Wipe any dirt from the threads of the
spark plug.
3) Install the spark plug, and then
tighten it to the specified torque.
4) Wipe off any water on the spark plug
or inside the spark plug cap, and
then install the cap. Push the spark
plug cap down until it is securely
installed.
Standard spark plug:
CR9EB
1 Spark plug gap
Spark plug tightening torque
12.5 Nm (9.2 ft-lb) (1.27 kgf-m)
Spark plug gap:
0.7~0.8mm (0.028~0.031 in)