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:
Identification
Vehicle identification number
The vehicle identification number "1" is stamped
into the right side of the steering head pipe.
Model label
The model label "1" is affixed to the frame. This
information will be needed to order spare parts.
...
Introduction
WARNINGDisc brake components rarely require
disassembly.
Therefore, always follow these preventive
measures:
Never disassemble brake components unless
absolutely necessary.
If any connection on the hydraulic brake
system is disconnected, the entire brake
sy ...
Setting the diagnostic mode
1. Set the main switch to "OFF" and the engine stop switch to "
".
2. Disconnect the self-diagnosis signal connector "1", and then connect the FI
diagnostic tool "2" as
shown.
3. Disconnect the fuel pump coupler.
4. While pressing the "MODE" button, set the main switch to "ON".
NOTE:
...