Checking The Piston - APRILIA QUASAR 125 2003 Workshop Manual

ENGINE
QUASAR 125-180

3.2.25 CHECKING THE PISTON

Remove piston rings taking care not to over-enlarge them.
Then, using a rounded scraper, remove any carbon deposits from piston
crown. To clean piston rings seats, use a waste piston ring.
Do not use silundum emery cloth to clean piston crowns or seats asa too high
amount of metal would be removed and the silundum particles settling inside
the piston will lead to an early wear of cylinder bore and thus to piston
corrosion.
Thoroughly inspect piston skirt. If hard carbon deposits are present, soak the
whole piston in a suitable liquid, such as that used to clean carburettors.
Hard carbon detergents are very dangerous; their vapours can cause
severe diseases and the contact with skin or eyes causes immediate
severe injuries. Always use the recommended protective equipment,
such as goggles and gloves and thoroughly follow the instructions and
the warnings written on the detergent container.
After cleaning, some light scores could still be present on the piston skirt. Do
not care.
In case of deep scores, change the piston.
Measure the piston diameter at 5 mm from piston lower edge using a
micrometer gauge, as shown.
Piston-cylinder coupling shall not be above 0.10 mm.
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Release 00/2003 - 09