Check that the walls of the cylinder are perfectly smooth. Measure the cylinder diameter at 50 mm from the top face and determine
the size class to which it belongs in accordance with the values specified in Section "Cylinder/piston".
Repeat measurement of the diameter at three heights "A" (10 mm from the upper surface), "B" (50 mm from the upper surface)
and "C" (100 mm from the upper surface) and in two directions at 90° between them; check that the measurements of taper and
ovality fall within the range specified in Section "Cylinder/piston".
In the event of damage or excessive wear the cylinder must be replaced as it has a silicon carbide coating (which provides
the cylinder walls with excellent anti-friction and anti-wear properties) and therefore cannot be ground.
The cylinders are marked with letters (stamped between the two oil return ways) indicating their size class.
Always match cylinders with pistons from the same size class.
Clean the piston crown and piston ring grooves, removing any carbon deposits.
Visually inspect the piston and check its dimensions carefully: there must be no signs of scuffing, scoring, cracks, or other
damage.
The piston diameter must be measured at 7.5 mm up from the bottom of the skirt and in perpendicular direction to the gudgeon
pin axis.
The pistons must always be replaced as a pair.
The pistons are marked with a symbol (selected letter (L) punched onto the piston crown) that indicates the size class to
which they belong.
Always match cylinders with pistons from the same size class.
(F): arrow that indicates the exhaust side.
For the correct values, refer to chapter "Cylinder/piston".
Gudgeon pins must be perfectly smooth without signs of scoring, steps, or blueing due to overheating.
The well-lubricated gudgeon pin must slide smoothly inside the piston without stiffness.
For the coupling clearance values with the piston and the connecting rod, see chapter "Cylinder/Piston".
If a new gudgeon pin is fitted, you must also change the connecting rod small end bush.