Yamaha YZF-R125 Service Manual: Checking the starter clutch
1. Check:
- Starter clutch rollers "1"
- Starter clutch spring caps "2"
- Starter clutch springs "3"
Damage/wear 
Replace the starter
clutch
assembly.
2. Check:
- Starter clutch idle gear
- Starter clutch gear Burrs/chips/roughness/wear Replace the defective part(s).
3. Check:
- Starter clutch gear contacting surfaces Damage/pitting/wear Replace the starter clutch gear.
4. Check:
- Starter clutch operation
a. Install the starter clutch gear "1" onto the starter clutch and hold the generator rotor.
b. When turning the starter clutch gear clockwise "A", the starter clutch and the starter clutch gear should engage, otherwise the starter clutch is faulty and must be replaced.
c. When turning the starter clutch gear counterclockwise
"B", it should turn freely, otherwise
the starter clutch is faulty and must be replaced.
Removing the starter clutch
1. Remove:
Starter clutch bolts "1"
NOTE:
While holding the generator rotor "2" with the
sheave holder "3", remove the starter clutch
bolts.
Do not allow the sheave holder to touch th ...
Installing the starter clutch
1. Install:
Starter clutch assembly
Starter clutch bolts "1"
NOTE:
While holding the generator rotor "2" with the
sheave holder "3", tighten the starter clutch
bolts.
Do not allow t ...
Other materials:
Troubleshooting
Although Yamaha motorcycles receive
a thorough inspection before shipment
from the factory, trouble may occur during
operation. Any problem in the fuel,
compression, or ignition systems, for
example, can cause poor starting and
loss of power.
The following troubleshooting charts
repre ...
Cleaning and lubricating the drive chain
The drive chain must be cleaned and
lubricated at the intervals specified in
the periodic maintenance and lubrication
chart, otherwise it will quickly wear
out, especially when riding in dusty or
wet areas. Service the drive chain as
follows.
NOTICE
The drive chain must be lubricated
...
Troubleshooting
Any of the following fail to light: headlight, high beam indicator light,
taillight, license plate light, auxiliary
light or meter light.
NOTE:
Before troubleshooting, remove the following part(s):
1. Seats
2. Fuel tank
...