Vittorazi Motors Moster 185 Plus Maintenance Manual page 116

The triangle on the top of the piston indicates the exhaust side.
Insert the roller bearing (10), the piston (9), the pin (8) and the circle clip (7).
Replace the O-ring (4) and the 4 self-locking nuts M8 (1) each time they are disassembled.
Fit the O-ring (4) on the head (3).
Moster 185 Plus - Maintenance manual - V1 116