Inspecting The Piston; Standard Coupling Clearance; Maximum Admitted Clearance After Use - PIAGGIO Liberty 125 Workshop Manual

Engine
Maximum allowable run-out:
0.05 mm
- The cylinder rectifying operation should be car-
ried out with a surfacing that respects the original
angle.
- The cylinder surface roughness should be 0.9
micron.
- This is indispensable for a good seating of the
sealing rings, which in turn minimises oil consump-
tion and guarantees optimum performance.
- The pistons are oversized due to cylinder rectifi-
cation and are subdivided into three categories
1st, 2nd, 3rd with 0.2-0.4-0.6 mm oversize. They
are also classified into 4 categories A-A, B-B, C-
C, D-D.

Inspecting the piston

- 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.
Name
Top piston ring
Middle piston ring
oil scraper

MAXIMUM ADMITTED CLEARANCE AFTER USE

Name
Top piston ring
Middle piston ring
oil scraper
ENG - 94

STANDARD COUPLING CLEARANCE

Description Dimensions
0.025 ÷ 0.070
0.015 ÷ 0.060
0.015 ÷ 0.060
Description Dimensions
0.080 mm
0.070 mm
0.070 mm
Liberty 125 - 200 4tempi
Initials Quantity
Initials Quantity