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EJU13421
Cleaning and adjusting the
spark plugs
The spark plug is an important engine
component and is easy to inspect. The con-
dition of the spark plug can indicate some-
thing 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. Have a Yamaha dealer service the
watercraft.
Remove and inspect the spark plugs peri-
odically; heat and deposits will cause the
spark plugs to slowly break down and erode.
If electrode erosion becomes excessive, or if
carbon and other deposits are excessive,
replace the spark plug with the specified
plug.
Measure the spark plug gap a with a
wire thickness gauge. Replace the spark
plugs or adjust the gap to specification if
necessary.
To install the 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. Install the spark plug cap.Standard spark plug: BR8HS
Spark plug gap:
0.6–0.7 mm (0.024–0.028 in)
Spark plug tightening torque:
25 N·m (2.5 kgf·m, 18 ft·lb)
E_F0M-70.book Page 14 Wednesday, June 23, 2004 4:52 PM
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NOTE:@ Wipe off any water on the spark plug or
inside the cap before installing the spark
plug cap. Push the spark plug cap down
until it is securely installed.
If a torque wrench is not available when
you are installing a new spark plug, a good
estimate of the correct torque is 1/4 turn to
1/2 turn past finger tight with the spark
plug wrench included in the tool kit. Have
the spark plug adjusted to the correct
torque with a torque wrench as soon as
possible.
@
WARNING@ Be careful not to damage the insulator
when removing or installing a spark plug.
A damaged insulator could allow sparks
to escape, which could lead to an explo-
sion or fire.
@
EJU11391
Lubrication points
To keep moving parts sliding or rotating
smoothly, coat them with water-resistant
grease.
Recommended water-resistant grease:
Yamaha Marine Grease/
Yamaha Grease A
Throttle cable (carburetor end)
Choke cable (carburetor end)
E_F0M-70.book Page 15 Wednesday, June 23, 2004 4:52 PM
