Yamaha YJ125S Service Manual page 249

EAS00742
4. Ignition spark gap
8 Disconnect the spark plug cap from the
spark plug.
8 Connect the ignition checker 1 as
shown.
2 Spark plug cap
8 Set the main switch to "ON".
8 Measure the ignition spark gap a.
8 Crank the engine by pushing the starter
switch and gradually increase the spark
gap until a misfire occurs.
Minimum ignition spark gap
6 mm(0.24 in)
8 Is there a spark and is the spark gap
within specification?
NO
The ignition system is OK.
IGNITION SYSTEM
EAS00744
YES
EAS00746
7-11
5. Spark plug cap resistance
8Remove the spark plug cap from the
spark plug lead.
8Connect the pocket tester ("Ω × 1k"
range) to the spark plug cap as shown.
8Measure the spark plug cap resistance.
Spark plug cap resistance
8~12 kΩ Ω Ω Ω Ω at 20°C
8Is the spark plug cap OK?
YES
Replace the spark plug cap.
6. Ignition coil resistance
8Disconnect the ignition coil connectors
from the ignition coil terminals.
8Connect the pocket tester (Ω × 1) to the
ignition coil as shown.
Positive tester probe
Negative tester probe
- +
ELEC
NO
orange
black