Yamaha YZF-R125 Service Manual: Removing the valves
The following procedure applies to all of the valves and related components.
NOTE:
Before removing the internal parts of the cylinder head (e.g., valves, valve springs, valve seats), make sure the valves properly seal.
1. Check:
- Valve sealing
Leakage at the valve seat
Check
the valve face, valve seat, and valve seat width.Refer to "CHECKING THE VALVE SEATS" on page 5-20.
a. Pour a clean solvent "a" into the intake and exhaust ports.
b. Check that the valves properly seal.
NOTE:
There should be no leakage at the valve seat "1".
2. Remove:
- Valve cotters "1"
NOTE:
Remove the valve cotters by compressing the
valve spring with the valve spring compressor
and the valve spring compressor attachment "2".
3. Remove:
- Upper spring seat "1"
- Valve spring "2"
- Valve "3"
- Valve stem seal "4"
- Lower spring seat "5"
NOTE:
Identify the position of each part very carefully so that it can be reinstalled in its original place.
Checking the valves and valve guides
The following procedure applies to all of the
valves and valve guides.
1. Measure:
Valve-stem-to-valve-guide clearance
Out of specification Replace the
valve
guide.
Valve-stem-to-valve ...
Other materials:
Checking the rear brake disc
1. Remove:
Rear wheel
Refer to "REAR WHEEL" on page 4-12.
2. Check:
Brake disc
Damage/galling → Replace.
3. Measure:
Brake disc deflection
Out of specification → Correct the brake
disc
deflection or replace the brake disc.
Refer to "CHECKING THE FRONT BRAKE
DIS ...
Installing the exhaust assembly
1. Install:
Exhaust assembly "1"
Exhaust pipe nuts "2"
Exhaust assembly bolts "3" "4"
NOTE:
Do not fully tighten the nuts and bolts.
2. Tighten:
Exhaust pipe nuts "2"
Exhaust assembly bolt "4"
Exhaust assembly bolt "3"
...
Removing the front brake caliper
NOTE:
Before disassembling the brake caliper, drain
the brake fluid from the entire brake system.
1. Remove:
Brake hose union bolt "1"
Copper washers "2"
Brake hose "3"
NOTE:
Put the end of the brake hose into a container
and pump out the brake fluid carefully.
...