Yamaha YZF-R125 Service Manual: Installing the valves
The following procedure applies to all of the valves and related components.
1. Deburr:
- Valve stem end (with an oil stone)
2. Lubricate:
- Valve stem "1"
- Valve stem seal "2"
(with the recommended lubricant)
3. Install:
- Lower spring seat "1"
- Valve stem seal "2"
- Valve "3"
- Valve spring "4"
- Upper spring seat "5" (into the cylinder head)
NOTE:
- Make sure each valve is installed in its original place.
- Install the valve springs with the larger pitch "a" facing up.
b. Smaller pitch
4. Install:
- Valve cotters "1"
NOTE:
Install the valve cotters by compressing the
valve spring with the valve spring compressor
and the valve spring compressor attachment "2".
5. To secure the valve cotters onto the valve stem, lightly tap the valve tip with a soft-face hammer.
| CAUTION: Hitting the valve tip with excessive force could damage the valve. |
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 ...
Other materials:
Coolant
The coolant level should be checked
before each ride. In addition, the coolant
must be changed at the intervals
specified in the periodic maintenance
and lubrication chart.
To check the coolant level
Place the vehicle on a level surface
and hold it in an upright position.
TIP
...
Drive chain slack
The drive chain slack should be
checked before each ride and adjusted
if necessary.
To check the drive chain slack
Place the motorcycle on the sidestand.
TIP
When checking and adjusting the drive
chain slack, there should be no weight
on the motorcycle.
Shift the transmission in ...
Checking the ignition spark gap
1. Check:
Ignition spark gap
Out of specification Perform the
ignition
system troubleshooting, starting with step 5.
Refer to "TROUBLESHOOTING" on page
8-3.
NOTE:
If the ignition spark gap is within specification,
the ignition system circuit is operating normally.
a. Disconnect the spa ...