On this parts fiche the Circlip-piston Pin is the most specified component.
A sample from the products for the Cylinder/piston(s) include: Cylinder-engine, Nut, Washer,9x15.5x2, Ring-set-piston.
The twelve Er650ecf Er6n 2012 Europe,middle East,africa Cylinder/piston(s) component parts are all listed in this schematic.