Yamaha YZ450FF 1SL-28199-11, Owner'S Service Manual

Page: 331 / 358

ELECTRICAL COMPONENTS
8-41
EAS1SL5337
CHECKING THE IGNITION SPARK GAP
1. Check:
• Ignition spark gap
Out of specification

Perform the ignition
system troubleshooting.
Refer to “TROUBLESHOOTING” on page 8-
4.
TIP
If the ignition spark gap is within specification,
the ignition system circuit is operating normally.
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a. Remove the spark plug cap from the spark
plug.
b. Connect the ignition checker “1”.
c. Crank the engine, and measure the ignition
spark gap “a”.
d. Crank the engine, and gradually increase
the spark gap until a misfire occurs.
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EAS1SL5338 CHECKING THE SPARK PLUG CAP
1. Remove:
• Spark plug cap
(from the spark plug lead)
2. Check:
• Spark plug cap resistance
Out of specification

Replace.
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a. Connect the pocket tester (
 
1k) to the
spark plug cap.
b. Measure the spark plug cap resistance.
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EAS1SL5339
CHECKING THE IGNITION COIL
1. Disconnect:
• Ignition coil terminal
(from the sub wire harness)
• Spark plug cap
(from the ignition coil)
2. Check:
• Primary coil resistance
Out of specification

Replace.
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a. Connect the pocket tester (
 
1) to the igni-
tion coil.
Minimum ignition spark gap
6.0 mm (0.24 in)
Ignition checker
90890-06754
Oppama pet-4000 spark checker
YM-34487
2. Spark plug cap
Spark plug cap resistance
10 k

Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
Primary coil resistance
2.16–2.64

Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
• Positive tester probe

Ignition coil terminal 1 “1”
• Negative tester probe

Ignition coil terminal 2 “2”