Yamaha YZF-R125 Service Manual: Checking the clutch boss
1. Check:
Clutch boss splines
Damage/pitting/wear 
Replace the
clutch
boss.
NOTE:
Pitting on the clutch boss splines will cause erratic clutch operation.
Checking the pressure plate
1. Check:
Pressure plate
Cracks/damage 
Replace.
Checking the clutch push lever and short clutch push rod
1. Check:
- Clutch push lever
- Short clutch push rod
Damage/wear Replace the
defective part(s).
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
cl ...
Checking the primary drive gear
1. Remove:
Primary drive gear
Refer to "BALANCER GEAR" on page 5-53.
2. Check:
Primary drive gear
Damage/wear Replace the
primary drive
gear and clutch housing as a set.
...
Other materials:
Assembling the water pump
1. Install:
Water pump seal "1"
(into the water pump housing "2")
CAUTION:Never lubricate the water pump seal
surface
with oil or grease.
NOTE:
Install the water pump seal with the special
tools.
Install the water pump seal with the special
tools to the specifi ...
Checking the relays
Check each switch for continuity with the pocket
tester. If the continuity reading is incorrect, replace
the relay.
1. Disconnect the relay from the wire harness.
2. Connect the pocket tester ( × 1) and battery
(12 V) to the relay terminal as shown.
Check the relay operation.
Out ...
Starting circuit cut-off system operation
If the engine stop switch is set to "
" and the main switch is set to
"ON" (both switches are closed), the
starter motor can only operate if at least one of the following conditions is
met:
The transmission is in neutral (the neutral switch is closed).
The clutch lever is pulled to the ...