VESPA ET4 50, Workshop Manual

Page: 88 / 185

Refitting 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 perpen-
dicularly to the cylinder axis.
- Measure the opening, see figure, of the sealing
rings using a thickness gauge.
- If any measurements are greater than specified,
replace the piston rings.
N.B.
BEFORE REPLACING ONLY THE PISTON
RINGS, ENSURE THAT THE CLEARANCE BE-
TWEEN 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 COMBI-
NATION WITH A USED CYLINDER MAY HAVE
DIFFERENT BEDDING CONDITIONS THAN
THE STANDARD.
SEALING RINGS
Name Descripti
on
Dimensio
ns
Initials Quantity
Top piston
ring
0.08 ÷
0.20 mm
0.35 mm
Middle pis-
ton ring
0.05 ÷
0.20 mm
0.30 mm
oil scraper 0.20 ÷
0.70 mm
0.80 mm
Engine
ET4 50
ENG - 88