Yamaha YZF-R125 Service Manual: 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 brake pad "1", push down on the brake caliper bracket so that there is space to remove the brake pad.
2. Measure:
Brake pad wear limit "a"
Out of specification → Replace the brake
pads as a set. 
3. Install:
- Brake pad spring
- Brake pads
NOTE:
Always install new brake pads and a new brake pad spring as a set.
a. Connect a clear plastic hose tightly to the bleed screw. Put the other end of the hose into an open container.
b. Loosen the bleed screw and push the brake caliper piston into the brake caliper with your finger.
c. Tighten the bleed screw. 
d. Install a new brake pad spring "1" and new brake pads.
NOTE:
Install the brake pad spring as shown.
4. Install:
- Brake pad retaining bolts
- Brake caliper
5. Install:
- Rear wheel Refer to "REAR WHEEL" on page 4-12.
6. Check:
- Brake fluid level
Below the minimum level mark "a"
Add the
recommended brake fluid to the proper level.Refer to "CHECKING THE BRAKE FLUID LEVEL" on page 3-18.
7. Check:
- Brake pedal operation
Soft or spongy feeling Bleed
the brake system.Refer to "BLEEDING THE HYDRAULIC BRAKE SYSTEM" on page 3-20.
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 → Correc ...
Removing the rear brake caliper
NOTE:
Before disassembling the brake caliper, drain
the brake fluid from the entire brake system.
1. Remove:
Union bolt "1"
Copper washers "2"
Brake hose "3"
NOTE:
Put the end of th ...
Other materials:
Checking the ignition coil
1. Check:
Primary coil resistance
Out of specification Replace.
a. Disconnect the ignition coil connectors from
the ignition coil terminals.
b. Connect the pocket tester ( × 1)
to the ignition
coil as shown.
Positive tester probe
red/white "1"
Negative tester probe
orange ...
Disassembling the water pump
1. Remove:
Water pump seal "1"
NOTE:
Remove the water pump seal from the inside of
the water pump housing "2".
2. Remove:
Bearing "1"
NOTE:
Remove the bearing from the outside of the water
pump housing "2".
...
Checking the piston rings
1. Measure:
Piston ring side clearance
Out of specification Replace the
piston
and piston rings as a set.
NOTE:
Before measuring the piston ring side clearance,
eliminate any carbon deposits from the piston
ring grooves and piston rings.
2. Install:
Piston ring
(into the cylind ...