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:
Checking the starter clutch
1. Check:
Starter clutch rollers "1"
Starter clutch spring caps "2"
Starter clutch springs "3"
Damage/wear Replace the starter
clutch
assembly.
2. Check:
Starter clutch idle gear
Starter clutch gear
Burrs/chips/roughness/wear Replace the
defective part(s).
3. Check:
...
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 ...
Installing the drive chain
1. Lubricate:
Drive chain
Master link
2. Install:
Drive sprocket
Drive sprocket retainer bolts
3. Install:
Master link
O-rings
Master link plate
Master link clip "1"
CAUTION:
The closed end of the master link clip must
face in the direction of drive ch ...