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:
Faulty front fork legs
Leaking oil
- Bent, damaged or rusty inner tube
- Cracked or damaged outer tube
- Improperly installed oil seal
- Damaged oil seal lip
- Incorrect oil level (high)
- Loose damper rod assembly bolt
- Damaged damper rod assembly bolt copper
washer
- Cracked or damaged front fork cap O-ring
M ...
Checking the cylinder head breather hose
1. Remove:
Left side panel
Refer to "GENERAL CHASSIS" on page 4-1.
2. Check:
Cylinder head breather hose "1"
Cracks/damage → Replace.
Loose connection → Connect properly.
CAUTION:Make sure the cylinder head
breather hose is
routed correctly.
...
Handlebar switches
Left
Left
1. Pass switch "PASS"
2. Dimmer switch "/"
3. Turn signal switch "/"
4. Horn switch""
Right
Right
Engine stop switch "/"
Start switch""
Pass switch "PASS"
Press this switch to flash the headlight.
Dimmer switch "/"
Set this switch to""
for the high
beam an ...