Yamaha F40BMHD, Service Manual

Page: 454 / 537

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ELEC
8-12
IGNITION SYSTEM
E
CHECKING THE SPARK PLUGS
Refer to "CHECKING THE SPARK PLUGS"
on page 3-22.
CHECKING THE IGNITION SPARK GAP
WARNING
• Do not touch any of the connections of
the spark gap tester lead wires.
• Do not let sparks leak out of the
removed spark plug cap.
• Keep flammable gas or liquids away,
since this test can produce sparks.
Check:
• Ignition spark gap
Above specification
→
Replace the
spark plug.
Checking steps
(1) Remove the spark plugs from the engine.
(2) Connect a spark plug cap to the spark
gap tester.
(3) Set the spark gap length on the adjust-
ing knob.
(4) Crank the engine and observe the spark
through the discharge window of the
spark gap tester.
Ignition spark gap
0.9 mm (0.04 in)
Spark gap tester
YM-34487/90890-06754