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:
Checking the steering head
1. Wash:
Bearings
Bearing races
2. Check:
Bearings
Bearing races
Damage/pitting →Replace.
3. Replace:
Bearings
Bearing races
a. Remove the bearing races from the steering
head pipe with a long rod "1" and hammer.
b. Remove the bearing race from the lower
bracket ...
Checking the ignition timing
NOTE:
Prior to checking the ignition timing, check the
wiring connections of the entire ignition system.
Make sure all connections are tight and free of
corrosion.
1. Remove:
Rider seat
Left lower side cowling
Refer to "GENERAL CHASSIS" on page 4-1.
2. Remove:
Timing mark acces ...
Checking the cylinder and piston
1. Check:
Piston wall
Cylinder wall
Vertical scratches Replace the
cylinder,
and replace the piston and piston rings as a
set.
2. Measure:
Piston-to-cylinder clearance
a. Measure cylinder bore "C" with the cylinder
bore gauge.
NOTE:
Measure cylinder bore "C" by takin ...