Lock the special tool with the clamp.
- Specific tooling: AP8140302 tool for sealing ring fitting
![](https://motoinstruction.ru/img/aprilia/17/123095.jpg)
Temporarily, fit the piston to the cylinder, without base or head gasket.
Remove the clamp from the sealing ring locking tool.
Remove the special tool for locking the connecting rod.
![](https://motoinstruction.ru/img/aprilia/17/123096.jpg)
Fit a dial gauge on the specific tool.
Set the dial gauge to zero on a reference surface with a medium preload, e.g. 5 mm (0.2 in). Keeping the zero setting, fit the tool on the cylinder and lock it with two nuts (10 Nm - 7.38 lb ft) as shown in the figure.
![](https://motoinstruction.ru/img/aprilia/17/123097.jpg)
- Specific tooling: 020714Y Dial gauge mounting
Rotate the crankshaft up to the TDC (the reversal point of the dial gauge rotation).
Lock the crankshaft at TDC using the specific tool.
![](https://motoinstruction.ru/img/aprilia/17/123098.jpg)
Calculate the difference between the two measurements: using the chart below, identify the thickness of the cylinder base gasket to be used upon refitting. By correctly identifying the cylinder base gasket thickness, an adequate compression ratio can be maintained.
Remove the specific tool and the cylinder.
- Specific tooling: 020720Y Timing tool
Base gasket
Specification | Desc./Quantity |
Measured protrusion -0.10 / + 0.0 mm (- 0.0039 / 0.0000 in) | Gasket 0.4 mm (0.0157 in) |
Measured protrusion 0.05 / 0.10 mm (0.0020 / 0.0039 in) | Gasket 0.5 mm (0.0197 in) |
Measured protrusion 0.15 / 0.30 mm (0.0059 / 0.0118 in) | Gasket 0.6 mm (0.0236 in) |