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 rear brake caliper
1. Check:
Brake caliper piston "1"
Rust/scratches/wear Replace the
brake
caliper piston.
Brake caliper cylinder "2"
Scratches/wear Replace the
brake caliper
assembly.
Brake caliper body "3"
Cracks/damage Replace the
brake caliper
assembly.
Brake fluid deli ...
Checking the cooling system
1. Remove:
Side covers
Upper side cowlings
Refer to "GENERAL CHASSIS" on page 4-1.
2. Check:
Radiator "1"
Radiator inlet hose "2"
Radiator outlet hose "3"
Coolant reservoir hose "4"
Water pump breather hose "5"
Cracks/damage → Replace.
Refer to "RADIATOR" on page 6-1 ...
Cleaning the air filter element
NOTE:
There is a check hose "1" at the bottom of the air
filter case. If dust and/or water collects in this
hose, clean the air filter element and air filter
case.
1. Remove:
Rider seat
Refer to "GENERAL CHASSIS" on page 4-1.
2. Remove:
Fuel tank
Refer to "FUEL TANK" on page ...