Honda CBR125R Owner's Manual page 349

Remove the push rod, master piston/spring and
separate them.
Clean the inside of the master cylinder and master
piston with brake fluid.
INSPECTION
Check the master cylinder for scoring, scratches or
damage.
Check the master piston for scoring, scratches or
damage.
Check the piston cups for wear, deterioration or
damage.
Measure the master cylinder I.D.
SERVICE LIMIT: 12.755 mm (0.5022 in)
Measure the master piston O.D.
SERVICE LIMIT: 12.645 mm (0.4978 in)
Check the following:
– Push rod for bent
– Boot for damage
– Rod joint for damage
Remove the pin and replace the damaged part if
necessary.
HYDRAULIC BRAKE
MASTER CYLINDER
SPRING
MASTER CYLINDER
PISTON CUPS
PUSH ROD
BOOT
PISTON
PUSH ROD
MASTER PISTON
ROD JOINT
PIN
15-17