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:
Checking the cylinder head
1. Eliminate:
Combustion chamber carbon deposits
(with a rounded scraper)
NOTE:
Do not use a sharp instrument to avoid damaging
or scratching:
Spark plug bore threads
Valve seats
2. Check:
Cylinder head
Damage/scratches Replace.
Cylinder head water jacket
Min ...
Removing the generator
1. Remove:
Generator rotor nut "1"
Washer
NOTE:
While holding the generator rotor "2" with the
sheave holder "3", loosen the generator rotor
nut.
Do not allow the sheave holder to touch the
projection on the generator rotor.
2. Remove:
Generator rotor "1"
(with the ...
Removing the primary drive gear and balancer gears
1. Loosen:
Primary drive gear nut "1"
NOTE:
Place the aluminum plate "a" between the balancer
drive gear "2" and the balancer driven
gear "3", and then loosen the primary drive gear
nut.
2. Straighten the lock washer tab.
3. Loosen:
Balancer driven gear nut "1"
NOTE:
Place ...