Yamaha YW50AP Service Manual page 174

3. Charging voltage
8 Connect the inductive tachometer to the
spark plug lead.
8 Connect the pocket tester (DC20V) to the
battery.
Tester (+) lead→Battery (+) terminal
Tester (-) lead→Battery (–) terminal
8 Start the engine and accelerate to about
5,000 r/min.
8 Check charging voltage.
Charging voltage:
13 ~ 14 V at 4,000 r/min
NOTE:
Use a full charged battery.
4. Charging coil and lighting coil resistance
8 Disconnect the charging coil coupler from
the wireharness.
8 Connect the pocket tester "Ω × 1" to the
charging coils.
8 Measure the charging coil and lighting coil
resistance.
Charging coil resistance:
Tester (+) lead→White lead 1
Tester (–) lead→Earth
Lighting coil resistance:
Tester (+) lead→Yellow/Red 2
Tester (–) lead→Earth
Charging coil resistance:
0.48~0.72 Ω at 20°C (68°F)
Lighting coil resistance:
0.4~0.6 Ω at 20°C (68°F)
*
OUT OF
SPECIFICATION
MEET
SPECIFICATION
*
CHARGING SYSTEM
MEETS SPECIFICATION
Charging circuit is good.
OUT OF SPECIFICATION
Charging coil is faulty, replace it.
7-16
– +
ELEC
1
W
CDI
Magneto
Y/R
2