Yamaha YZF-R125 Service Manual: Checking the rocker arms and rocker arm shafts
The following procedure applies to all of the rocker arms and rocker arm shafts.
1. Check:
- Rocker arm
Damage/wear
Replace.
2. Check:
- Rocker arm shaft
Blue discoloration/excessive wear/pitting/
scratches
Replace or
check the lubrication system.
3. Measure:
- Rocker arm inside diameter "a"
Out of specification
Replace.
4. Measure:
- Rocker arm shaft outside diameter "a"
Out of specification Replace.
5. Calculate:
- Rocker-arm-to-rocker-arm-shaft clearance
NOTE:
Calculate the clearance by subtracting the rocker arm shaft outside diameter from the rocker arm inside diameter.
Out of specification 
Replace the
defective
part(s).
Checking the camshaft
1. Check:
Camshaft lobes
Blue discoloration/pitting/scratches
Replace
the camshaft.
2. Measure:
Camshaft lobe dimensions "a" and "b"
Out of specification Replace
the cams ...
Installing the camshaft and rocker arms
1. Lubricate:
Rocker arms
Rocker arm shafts
2. Lubricate:
Camshaft
3. Install:
Camshaft "1"
NOTE:
Make sure that the camshaft projections "a" and
hole "b" are positioned as s ...
Other materials:
Checking the clutch plates
The following procedure applies to all of the
clutch plates.
1. Check:
Clutch plate
Damage Replace the clutch
plates as a
set.
2. Measure:
Clutch plate warpage
(with a surface plate and thickness gauge "1")
Out of specification Replace
the clutch
plates as a set.
...
Circuit diagram
2. Crankshaft position sensor
4. Main fuse
5. Main switch
6. Radiator fan motor fuse
8. Sidestand switch
9. Battery
17.Engine stop switch
19.Intake air pressure sensor
20.Intake air temperature sensor
21.Throttle position sensor
22.Coolant temperature sensor
23.Lean angle sensor
24.S ...
Troubleshooting
Any of the following fail to light: turn signal lights, brake light or
indicator lights.
The horn fails to sound.
The fuel gauge fails to operate.
The speedometer fails to operate.
NOTE:
Before troubleshooting, remove the following part(s):
1. Seats
2. Fuel tank
3. Left upper ...