PIAGGIO X9 Evolution 125 2008 - Page 120

- 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
56.945 ÷ 56.973 mm
Fitting clearance
Top piston ring - standard coupling clearance
0.025 ÷ 0.07 mm Top piston ring - maximum clear-
ance allowed after use 0.08 mm Middle piston
ring - standard coupling clearance 0.015 - 0.06 mm
Middle piston ring - maximum clearance al-
lowed after use 0.07 mm oil scraper ring - stand-
ard coupling clearance 0.015 - 0.06 mm oil scraper
ring - maximum clearance allowed after use
0.07 mm
Inspecting the piston rings
- Alternately insert the three sealing rings into the cylinder, in the area where it retains its original di-
ameter. Using the piston, insert the rings perpendicularly to the cylinder axis.
- Measure the opening (see figure) of the sealing rings using a feeler gauge.
- If any measurements are greater than specified, replace the piston rings.
N.B.
BEFORE REPLACING ONLY THE PISTON RINGS, ENSURE THAT THE CLEARANCE BETWEEN
THE PISTON RINGS AND THE PISTON RING GROOVES, AND BETWEEN THE PISTON AND THE
CYLINDER, IS AS SPECIFIED. IN ANY CASE, NEW PISTON RINGS USED IN COMBINATION WITH
A USED CYLINDER MAY HAVE DIFFERENT BEDDING CONDITIONS THAN THE STANDARD.
Engine X9 Evolution 125
ENG - 120