Yamaha 2004 WR250FS Owner's Service Manual page 302

IGNITION SYSTEM
EC626002
IGNITION COIL INSPECTION
1. Remove the ignition coil cap.
2. Inspect:
• Primary coil resistance
Out of specification → Replace.
Tester (+) lead → Orange lead 1
Tester (–) lead → Black lead 2
Primary coil
resistance
0.08 ~ 0.10 Ω at
20 °C (68 °F)
3. Inspect:
• Secondary coil resistance
Out of specification → Replace.
Tester (+) lead → Orange lead 1
Tester (–) lead → Spark plug terminal 2
Secondary coil
resistance
4.6 ~ 6.8 kΩ at
20 °C (68 °F)
4. Inspect:
• Sealed portion of ignition coil a
• Spark plug terminal pin b
• Threaded portion of spark plug c
Wear → Replace.
6 - 6
– +
ELEC
Tester selector
position
Ω × 1
Tester selector
position
kΩ × 1