Yamaha YZF-R125 Service Manual: Installing the piston and cylinder
1. Install:
- Top ring "1"
- 2nd ring "2"
- Oil ring expander "3"
- Lower oil ring rail "4"
- Upper oil ring rail "5"
NOTE:
Be sure to install the piston rings so that the manufacturer marks or numbers face up.
2. Install:
- Piston "1"
- Piston pin "2"
- Piston pin clips "3"
NOTE:
- Apply engine oil to the piston pin.
- Make sure the arrow mark "a" on the piston points towards the exhaust side of the cylinder.
- Before installing the piston pin clips, cover the crankcase opening with a clean rag to prevent the clips from falling into the crankcase.
3. Lubricate:
- Piston
- Piston rings
- Cylinder
(with the recommended lubricant)
4. Offset:
- Piston ring end gaps
a. Top ring
b. Upper oil ring rail
c. Oil ring expander
d. Lower oil ring rail
e. 2nd ring
f. 20 mm (0.79 in)
A. Intake side
5. Install:
- Dowel pins
- Cylinder head gasket
- Cylinder "1"
NOTE:
- While compressing the piston rings with one hand, install the cylinder with the other hand.
- Pass the timing chain and timing chain guide (intake side) through the timing chain cavity.
Checking the piston pin
1. Check:
Piston pin
Blue discoloration/grooves
Replace the
piston pin and then check the lubrication system.
2. Measure:
Piston pin outside diameter "a"
Out of specification ...
Other materials:
Adjusting the valve clearance
The following procedure applies to all of the
valves.
NOTE:
Valve clearance adjustment should be made
on a cold engine, at room temperature.
When the valve clearance is to be measured or
adjusted, the piston must be at top dead center
(TDC) on the compression stroke.
1. Remove:
...
Disassembling the water pump
1. Remove:
Water pump seal "1"
NOTE:
Remove the water pump seal from the inside of
the water pump housing "2".
2. Remove:
Bearing "1"
NOTE:
Remove the bearing from the outside of the water
pump housing "2".
...
Removing the generator
1. Remove:
Generator rotor nut "1"
Washer
NOTE:
While holding the generator rotor "2" with the
sheave holder "3", loosen the generator rotor
nut.
Do not allow the sheave holder to touch the
projection on the generator rotor.
2. Remove:
Generator rotor "1"
(with the ...