Piston -POLINI 133cc Evolution- Vespa PV125, ET3 125, PK125 - 57mm

TIP: Always mount piston rings carefully. Piston rings made of cast material are only partially elastic and break relatively quickly.
Some pistons have trapezoidal profiled piston rings (so-called keystone rings), which only fit in one mounting position. If the ring is not free to move, please loosen it carefully and reinstall it turned 'upside down'.