Derbi boulevard 125 4t Workshop Manual page 19

Characteristics
Slot packing system
- Provisionally fit the piston into the cylinder, without any base gasket.
- Fit a dial gauge on the specific tool
- Set the dial gauge to zero at a contrast plane with an average precharge, for example 5 mm. Keeping
the zero setting position, fit the tool on the cylinder and lock it with 2 nuts, as shown in the figure.
- Rotate the crankshaft until TDC (the inverted point of the dial gauge rotation)
- Calculate the difference between the two measurements: use the chart below to identify the thickness
of the cylinder base gasket to be used for refitting. By correctly identifying the cylinder base gasket
thickness, an adequate compression ratio is maintained.
- Remove the specific tool and the cylinder.
Characteristic
Compression ratio (125)
10.6 : 1
Compression ratio
10.5: 1
Specification
Value measured
Thickness
Value measured
Thickness
Value measured
Thickness
SHIMMING SYSTEM (125)
Desc./Quantity
0 ÷ 0.1
0.8 ± 0.05
0.1 ÷ 0.3
0.6 ± 0.05
0.3 - 0.4
0.4 ± 0.05
CHAR - 19