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 primary driven gear
1. Check:
Primary driven gear "1"
Damage/wear Replace the
primary drive
gear and clutch housing as a set.
Excessive noise during operation
Replace
the primary drive gear and clutch housing as
a set.
...
Shifting
Shifting
Shift pedal
Neutral position
Shifting gears lets you control the
amount of engine power available for
starting off, accelerating, climbing hills,
etc.
The gear positions are shown in the illustration.
TIP
To shift the transmission into the neutral
position, press the ...
Removing the piston
1. Remove:
Piston pin clips "1"
Piston pin "2"
Piston "3"
CAUTION:Do not use a hammer to drive the piston
pin
out.
NOTE:
Before removing the piston pin clip, cover the
crankcase opening with a clean rag to prevent
the piston pin clip from falling in ...