Checking The Ignition Spark Gap; Checking The Spark Plug Cap; Checking The Ignition Coil - Yamaha YZ450FP 2023 Owner's Service Manual

b. Connect the digital circuit tester () to the
diode coupler as shown.
c. Check the diode for continuity.
d. Check the diode for no continuity.
Br/W
L/W,
L
EAM30294

CHECKING THE IGNITION SPARK GAP

1. Check:
• Ignition spark gap
Out of specification  Perform the ignition
system troubleshooting, starting with step (5).
Refer to "TROUBLESHOOTING" on page
8-3.
Minimum ignition spark gap
6.0 mm (0.24 in)
TIP
If the ignition spark gap is within specification,
the ignition system circuit is operating normally.
a. Remove the spark plug cap from the spark
plug.
b. Connect the ignition checker "1" as
shown.
Ignition checker
90890-06754
Oppama pet–4000 spark checker
YM-34487
c. Crank the engine, and measure the igni-
tion spark gap "a".
2. Spark plug cap
d. Crank the engine, and gradually increase
1
2
8-50
ELECTRICAL COMPONENTS
the spark gap until a misfire occurs.
EAM30295

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.
Resistance
10.00 k
a. Connect the digital circuit tester () to the
spark plug cap.
Digital circuit tester (CD732)
90890-03243
Model 88 Multimeter with tachom-
eter
YU-A1927
b. Measure the spark plug cap resistance.
EAM30296

CHECKING THE IGNITION COIL

1. Disconnect:
• Ignition coil terminal
(from the wire harness)
• Spark plug cap
(from the ignition coil)
2. Check:
• Primary coil resistance
Out of specification  Replace.
Primary coil resistance
1.98–2.42 
a. Connect the digital circuit tester () to the
ignition coil.
Digital circuit tester (CD732)
90890-03243
Model 88 Multimeter with tachom-
eter
YU-A1927