Yamaha YZF-R125 Service Manual: 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 opening pressure
Below the specified pressure
Replace the radiator cap.
a. Install the radiator cap tester "1" and radiator
cap tester adapter "2" to the radiator cap "3".
b. Apply the specified pressure for ten seconds and make sure there is no drop in pressure.
4. Check:
- Radiator fan
Damage
Replace.
Malfunction
Check and repair.Refer to "COOLING SYSTEM" on page 8-25.
Radiator
...
Installing the radiator
1. Fill:
Cooling system
(with the specified amount of the recommended
coolant)
Refer to "CHANGING THE COOLANT" on
page 3-15.
2. Check:
Cooling system
Leaks Repair or replace any
...
Other materials:
Checking the clutch housing
1. Check:
Clutch housing dogs "1"
Damage/pitting/wear
Deburr the clutch
housing dogs or replace the clutch housing.
NOTE:
Pitting on the clutch housing dogs will cause erratic
clutch operation.
2. Check:
Bearing
Damage/wear Replace the
bearing and
clutch housin ...
Removing the swingarm
1. Stand the vehicle on a level surface.
WARNINGSecurely support the vehicle
so that there is
no danger of it falling over.
NOTE:
Place the vehicle on a suitable stand so that the
rear wheel is elevated.
2. Measure:
Swingarm side play
Swingarm vertical movement
a. Me ...
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".
...