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:
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
...
Sidestand
The sidestand is located on the left side
of the frame. Raise the sidestand or
lower it with your foot while holding the
vehicle upright.
TIP
The built-in sidestand switch is part of
the ignition circuit cut-off system, which
cuts the ignition in certain situations.
WARNING
The vehicl ...
Adjusting the engine idling speed
The engine idling speed must be
checked and, if necessary, adjusted as
follows at the intervals specified in the
periodic maintenance and lubrication
chart.
The engine should be warm before
making this adjustment.
Remove panel A.
Check the engine idling speed
and, if necessary, ...