Inspecting The Wrist Pin; Inspecting The Piston - PIAGGIO MSS X9 EVOLUTION 250 Workshop Manual

Engine

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

- 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.
- Take the measurement at 5 mm from the base in
the position shown in the figure.
- Carefully clean the seal housings.
- Measure the coupling clearance between the
sealing rings and the grooves using suitable sen-
sors, as shown in the diagram.
- If the clearance is greater than that indicated in
the table, replace the piston.
N.B.
MEASURE THE CLEARANCE BY INSERTING THE BLADE
OF THE FEELER THICKNESS GAUGE FROM THE SECOND
SEAL SIDE.
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
ENG - 112
MSS X9 Evolution 250