Derbi boulevard 125 4t Workshop Manual page 112

Engine
- With the opening in position indicated on the tool,
take stop ring in the closed position using the
punch.
- Fit the wrist pin stop using the plug as shown in
the figure
N.B.
THE TOOL FOR INSTALLING THE STOP
RINGS MUST BE USED MANUALLY.
CAUTION
USING A HAMMER TO POSITION THE RINGS
CAN DAMAGE THE LOCKING HOUSING.
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 tapered side of the middle piston ring should
always be facing away from the crown of the pis-
ton.
- 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.
SO AS TO OBTAIN THE BEST CONFIGURA-
TION THE 2 SEALING RINGS ARE MADE WITH
A CONTACT CONICAL CYLINDER SECTION.
ENG - 112