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 valve seats
The following procedure applies to all of the
valves and valve seats.
1. Eliminate:
Carbon deposits
(from the valve face and valve seat)
2. Check:
Valve seat
Pitting/wear Replace the
cylinder head.
3. Measure:
Valve seat width C "a"
Out of specification Replace
the ...
Shifting
Shifting
Shift pedal
Neutral position
Shifting gears lets you control the
amount of engine power available for
starting off, accelerating, climbing hills,
etc.
The gear positions are shown in the illustration.
TIP
To shift the transmission into the neutral
position, press the ...
Setting the normal mode
NOTE:
The engine speed, coolant temperature, and fault code, if detected, can be
displayed on the LCD of the
FI diagnostic tool when the tool is connected to the vehicle and is set to the
normal mode.
1. Set the main switch to "OFF" and the engine stop switch to "".
2. Disconnect the self- ...