PIAGGIO B 250 - Inspecting the Piston

Inspecting the wrist pin
- Measure the outside diameter of the gudgeon
pin.
- Calculate the coupling clearance between pin
and connecting rod end.
Characteristic
Pin diameter: Standard clearance
0.015 ÷ 0.029 mm
Pin diameter Standard diameter
14.996 - 15.000 mm
Inspecting the piston
Version 125
- Measure the diameter of the wrist pin seat on the
piston.
- Calculate the piston pin coupling clearance.
- Measure the outside diameter of the piston, per-
pendicular to the gudgeon pin axis.
- Measure at 41.1 mm from the piston crown in the
position shown in the figure.
- Carefully clean the seal housings.
- Measure the coupling clearance between the
seal rings and the grooves using suitable sensors,
as shown in the diagram.
- If the clearance is greater than that indicated in
the table, replace the piston.
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
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
piston diameter
B 125-250 Engine
ENG - 145