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:
Introduction
Welcome to the Yamaha world of motorcycling!
As the owner of the YZF-R125, you are benefiting from Yamaha's vast
experience and newest technology regarding the design
and manufacture of high-quality products, which have earned Yamaha a reputation
for dependability.
Please take the time to re ...
Disassembling the front fork legs
The following procedure applies to both of the
front fork legs.
1. Remove:
Rubber cap
Clip "1"
Front fork cap "2"
(with O-ring)
Fork spring
NOTE:
Push the front fork cap in the direction of the arrow
shown in the illustration to remove the clip.
2. Drain:
Fork oil
NOTE ...
Checking the camshaft
1. Check:
Camshaft lobes
Blue discoloration/pitting/scratches
Replace
the camshaft.
2. Measure:
Camshaft lobe dimensions "a" and "b"
Out of specification Replace
the camshaft.
3. Check:
Camshaft oil passage
Obstruction Blow out with
compressed air. ...