Yamaha YP400T Service Manual page 341

EAS00742
4. Ignition spark gap
• Disconnect the spark plug cap from the
spark plug.
• Connect the ignition checker 1 as shown.
2 Spark plug cap
• Set the main switch to "ON".
• Measure the ignition spark gap a.
• Crank the engine by pushing the start
switch and gradually increase the spark
gap until a misfire occurs.
Minimum ignition spark gap
6 mm (0.24 in)
• Is there a spark and is the spark gap within
specification?
YES NO
The ignition system
is OK.
8 - 10
IGNITION SYSTEM
EAS00744
5. Spark plug cap resistance
• Remove the spark plug cap from the spark
plug lead.
• Connect the pocket tester (Ω × 1k) to the
spark plug cap as shown.
• Measure the spark plug cap resistance.
Spark plug cap resistance
10 kΩ at 20 °C (68 °F)
• Is the spark plug cap OK?
YES
– +
ELEC
NO
Replace the spark
plug cap.