VESPA GT 125 Workshop Manual page 134

Engine
- The cylinder surface must exhibit a roughness of
0.9 micron.
- This is required for ensuring a good settling of the
sealing rings, thereby ensuring a low oil consump-
tion and excellent performance.
For engine 125 cc
- There are uprated pistons for the cylinder adjust-
ment, divided into three categories 1°, 2°, 3° equal
to 0.2-0.4-0.6 mm of uprating. These are classified
in the 4 categories A-A, B-B, C-C, D-D.
N.B.
THE PIN HOUSINGS HAVE 2 LUBRICATION CHANNELS.
FOR THIS REASON MEASUREMENT OF THE DIAMETER
MUST BE CARRIED OUT ACCORDING TO THE AXIS OF
THE PISTON.
Characteristic
Piston pin diameter: Standard diameter: 200 -
250 cc
68,990 ÷ 69,018
Pin diameter Standard diameter: 125 cc
56.997 ÷ 57.025
Piston pin diameter: Piston 200 - 250
68,933 ÷ 68,961 mm
piston diameter
56.945 ÷ 56.973 mm
Pin diameter: Standard clearance
0.015 ÷ 0.029 mm
Pin diameter Standard diameter
14.996 - 15.000 mm
Wrist pin seat on the piston: Standard diameter
15.001 ÷ 15.006 mm
Diameter of the wrist pin seat on the piston:
Standard clearance
0.001 ÷ 0.010 mm
ENG - 134
Vespa GT 125-200