Yamaha YZF-R125 Service Manual: Checking the rear brake disc
1. Remove:
- Rear wheel Refer to "REAR WHEEL" on page 4-12.
2. Check:
- Brake disc Damage/galling → Replace.
3. Measure:
Brake disc deflection Out of specification → Correct the brake disc deflection or replace the brake disc.
Refer to "CHECKING THE FRONT BRAKE
DISC" on page 4-21. 
4. Measure:
Brake disc thickness Measure the brake disc thickness at a few different locations.
Out of specification → Replace.
Refer to "CHECKING THE FRONT BRAKE
DISC" on page 4-21. 
5. Adjust:
- Brake disc deflection
Refer to "CHECKING THE FRONT BRAKE
DISC" on page 4-21.
6. Install:
- Rear wheel Refer to "REAR WHEEL" on page 4-12.
Introduction
WARNINGDisc brake components rarely require
disassembly.
Therefore, always follow these preventive
measures:
Never disassemble brake components unless
absolutely necessa ...
Replacing the rear brake pads
NOTE:
When replacing the brake pads, it is not necessary
to disconnect the brake hose or disassemble
the brake caliper.
1. Remove:
Brake pads
Brake pad spring
NOTE:
To remove the inner b ...
Other materials:
Checking the thermostat
1. Check:
Thermostat
Does not open at 80.5-83.5 C (176.9-182.3
F) Replace.
a. Suspend the thermostat "1" in a container "2"
filled with water.
b. Slowly heat the water "3".
c. Place a thermometer "4" in the water.
d. While stirring the water, observe the thermostat
and th ...
Checking the radiator
1. Check:
Radiator fins
obstruction clean.
Apply compressed air to the rear of the radiator.
Damage repair or replace.
NOTE:
Straighten any flattened fins with a thin, flat-head
screwdriver.
2. Check:
Radiator hoses
Cracks/damage Replace.
3. Measure:
Radiator cap ...
Checking the starter motor operation
1. Check:
Starter motor operation
Does not operate → Perform the electric
starting system troubleshooting, starting with
step 4.
Refer to "TROUBLESHOOTING" on page
8-9.
a. Connect the positive battery terminal "1" and
starter motor lead "2" with a jumper lead "3".
W ...