Yamaha YFM250RX 2008 Service Manual page 293

EBS01066
3. Charging voltage
• Connect the engine tachometer to on to the
ignition coil.
• Connect the pocket tester (DC 20 V) to the
battery as shown.
Positive tester probe →
positive battery terminal
Negative tester probe →
negative battery terminal
• Start the engine and let it run at approxi-
mately 5,000 r/min.
• Measure the charging voltage.
Charging voltage
14 V at 5,000 r/min
NOTE: NOTE:
Make sure the battery is fully charged.
• Is the charging voltage within specification?
NO
YES
The charging circuit
is OK.
7-26
CHARGING SYSTEM
EBS01100
4. Stator coil resistance
• Disconnect the AC magneto coupler from
the wire harness.
• Connect the pocket tester (Ω × 1) to the
charging coils.
Tester (+) lead → White terminal
Tester (–) lead → White terminal
Tester (+) lead → White terminal
Tester (–) lead → White terminal
Tester (+) lead → White terminal
Tester (–) lead → White terminal
• Measure the stator coil resistance.
Charging coil resistance:
0.688 ~ 1.032 Ω at 20°C (68°F)
YES
5. Wiring
• Check the entire charging system's wiring.
Refer to "CIRCUIT DIAGRAM".
• Is the charging system's wiring properly
connected and without defects?
YES
Replace the rectifier/
regulator.
ELEC
NO
Replace the pickup
coil/stator assembly.
NO
Replace the diode
and properly con-
nect or repair the
charging system's
wiring.