Yamaha YZF-R125 Service Manual: Charging system
Troubleshooting
The starter motor fails to turn.
NOTE:
Before troubleshooting, remove the following part(s):
1. Seats
2. Fuel tank
3. Left lower side cowling
4. Left upper side cowling
...
Circuit diagram
1. AC magneto
3. Rectifier/regulator
4. Main fuse
9. Battery ...
Other materials:
Checking the cylinder head
1. Eliminate:
Combustion chamber carbon deposits
(with a rounded scraper)
NOTE:
Do not use a sharp instrument to avoid damaging
or scratching:
Spark plug bore threads
Valve seats
2. Check:
Cylinder head
Damage/scratches Replace.
Cylinder head water jacket
Min ...
Assembling the rear brake caliper
WARNING
Before installation, all internal brake components
should be cleaned and lubricated
with clean or new brake fluid.
Never use solvents on internal brake components
as they will cause the brake caliper
piston dust seal and piston seal to swell
and distort.
...
Checking the rectifier/regulator
1. Check:
Rectifier/regulator output voltage
Out of specification → Replace the
rectifier/
regulator.
a. Set the engine tachometer to the spark plug
lead.
b. Connect the pocket tester (DC 20 V) to the
rectifier/regulator coupler as shown.
Positive tester probe
red "1"
Negat ...