Inspecting The Wrist Pin; Inspecting The Piston Rings - APRILIA RS4 125 Service Station Manual

Engine
- top ring: +0.03 / 0.062 mm (0.0012 / 0.0024 in)
- middle ring: +0.02 / 0.052 mm (0.0008 / 0.0020 in)
- oil scraper: +0.01 / 0.19 mm (0.0004 / 0.007480 in)
cylinder check
•
Using a bore meter, measure the cyl-
inder inside diameter at three different
points according to the directions
shown in the figure.
•
Check that the coupling surface with
the head is not worn or misshapen.
CAUTION
THE MARKING IS LOCATED ON THE PISTON CROWN.
Characteristic
Maximum run-out allowed:
0.05 mm
Coupling categories with cast-iron cylinder
NAME ABBREVIA
TION
Cylinder/Piston M
Cylinder/Piston N
Cylinder/Piston O
Cylinder/Piston P

Inspecting the wrist pin

•
Check the pin outside diameter.
Characteristic
Pin
Minimum diameter: 14.995 mm (0.590 in)
Standard diameter: 15.0000 +0/-0.0030 mm (0.00012 in)

Inspecting the piston rings

Specification
Compression ring (top)
Compression ring (middle)
ENG - 188
C -
YLINDER PISTON COUPLING CLEARANCE
CYLINDER
min max
58.010 58.017
58.017 58.024
58.024 58.031
58.031 58.038
ANELLI DI TENUTA
125 ³
CM
PISTON
CLEARANCE
min max
57.963 57.970
57.970 57.977
57.977 57.984
57.984 57.991
Desc./Quantity
0.2 / 0.35 mm (0.0079 / 0.014 in)
0.2 / 0.35 mm (0.0079 / 0.014 in)
RS4 125
FITTING
min max
0.040 0.054
0.040 0.054
0.040 0.054
0.040 0.054