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 crankshaft position sensor
1. Disconnect:
Crankshaft position sensor coupler
(from the wire harness)
2. Check:
Crankshaft position sensor resistance
Out of specification Replace
the crankshaft
position sensor/stator assembly.
a. Connect the pocket tester ( × 100) to the
crankshaft position sensor c ...
Checking the brake fluid level
Front brake
Front brake
Minimum level mark
Rear brake
Rear brake
Minimum level mark
Insufficient brake fluid may allow air to
enter the brake system, possibly causing
it to become ineffective.
Before riding, check that the brake fluid
is above the minimum level mark an ...
Checking the valve springs
The following procedure applies to all of the
valve springs.
1. Measure:
Valve spring free length "a"
Out of specification Replace the valve
spring.
2. Measure:
Compressed valve spring force "a"
Out of specification Replace the valve
spring.
b. Installed length
3. ...