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:
Self-diagnostic function table
If the ECU detects an abnormal signal from a sensor while the vehicle is
being driven, the ECU illuminates
the engine trouble warning light and provides the engine with alternate
operating instructions that
are appropriate for the type of malfunction.
When an abnormal signal is received fro ...
Replacing the headlight bulbs
The following procedure applies to the low beam
headlight bulb.
1. Remove:
Headlight bulb cover "1"
2. Remove:
Headlight bulb holder "1"
3. Remove:
Headlight bulb "1"
WARNINGSince the headlight bulb gets extremely
hot,
keep flammable products and your ...
Assembling the front brake caliper
WARNING
Before installation, all internal brake components
should be cleaned and lubricated
with clean or new brake fluid.
Never use solvents on internal brake components
as they will cause the brake caliper
dust seals and piston seals to swell and
distort.
...