Checking The Air Gap; Checking The Ignition Coil (Tci Unit, Primary) Resistance - Yamaha MX250 Service Manual

ELECTRICAL COMPONENTS
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a. Remove the spark plug cap from the high tension
cord.
b. Connect the digital circuit tester () to the spark
plug cap as shown.
Model 88 Multimeter with tachometer:
YU-A1927
Digital circuit tester (CD732):
90890-03243
• Positive tester probe 
Spark plug side "1"
• Negative tester probe 
High tension cord side "2"
c. Measure the spark plug cap resistance.
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CHECKING THE AIR GAP

1.
Check:
• Thickness between the magnet rotor and TCI unit.
Out of specification  Perform the TCI unit adjust-
ment steps.
(Refer to "INSTALLING THE TCI UNIT" on page
3-14)
TCI unit air gap:
0.4–0.6 mm (0.0157–0.0236 in)
CHECKING THE IGNITION COIL (TCI UNIT,
PRIMARY) RESISTANCE
1.
Check:
• Primary coil resistance
Out of specification  Replace.
Primary coil resistance:
0.8 
5-6
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