1999 Aprilia MA50 - MY50 Engine Repair Manual
Power Plant
Removing the cylinder head
Caution : The manufacturer assumes no responsibility for damage resulting from the use of unsuitable tools for the removal and refitting of the engine or any part of it.
When the engine is in place, the cylinder head, the cylinder, the piston and the reed valve can be exposed by removing the following parts: exhaust pipe, air filter casing, carburettor.
Drain all the coolant. (This operation must be performed before removing the engine from the chassis.)
Caution: : The coolant must not be disposed of in the environment. The disposal must be carried out in compliance with the regulations in force.
Remove the spark plug and the two pipes of the carburettor heating system with the four clamps. Loosen the four cylinder-head flanged locknuts (1) by unscrewing them a half turn at a time. Remove the cylinder head.
IMPORTANT: Remove the cylinder head with the two sealing rings (inner and outer). Before removing the two pipes of the carburettor heating system, pay special attention to the way they are connected so as to ensure proper refitting.
Removing the thermostat
Loosen the two screws (1) shown in the figure, remove the thermostat and check its mechanical condition.
IMPORTANT: Before removing the two thermostat fixing screws, ensure that they are not excessively encrusted with coolant residues. On account of their small size, the screws may break if overstressed. If necessary use a release agent.
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