Refitting The Piston Rings - PIAGGIO 633929(IT) Service Station Manual

MP3 125
- By means of the table shown in the specifications
chapter identify the cylinder base gasket thickness
to be used for refitting. The proper identification of
the cylinder base gasket thickness allows main-
taining the correct compression ratio.
- Remove the specific tool and the cylinder.
N.B.
MEASURE PISTON PROTRUSION.
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.
N.B.
THE TWO PISTON RINGS ARE MADE WITH A
TAPERED CYLINDRICAL CONTACT CROSS-
SECTION. THIS IS TO ACHIEVE A BETTER
BEDDING.
Engine
ENG - 37