Refitting The Piston Rings; Refitting The Cylinder - VESPA GT 125 Workshop Manual

Engine
der base gasket thickness to keep the correct
compression ratio.
- Remove the specific tool and the cylinder.
N.B.
PISTON PROTRUSION IS MEASURED IN 125 ENGINES
WHILE INTRODUCTION IS MEASURED IN 200 ENGINES.
See also
Slot packing system

Refitting the piston rings

- Place the oil scraper spring on the piston.
- Refit the oil scraper ring with the join of spring
ends on the opposite side from the ring gap and
the word 'TOP' towards the crown of the piston.
The chamfered side of the oil scraper ring should
always be facing the piston crown.
- Fit the middle piston ring with the identification
letter facing the crown of the piston. In any case,
the step must be facing opposite the piston top.
- Fit the top piston ring with the word 'TOP' or the
reference mark facing the crown of the piston.
- Offset the piston ring gaps on the three rings by
120° to each other as shown in the figure.
- Lubricate the components with engine oil.
- The 200 engine takes the 1st segment with L
section.
N.B.
THE TWO PISTON RINGS ARE MADE WITH A TAPERED
CYLINDRICAL CONTACT CROSS-SECTION. THIS IS TO
ACHIEVE A BETTER BEDDING.

Refitting the cylinder

- Insert the cylinder base gasket with the thickness determined above.
- Using the fork support and the piston ring retaining band, refit the cylinder as shown in the figure.
ENG - 138
Vespa GT 125-200