Flying Horse 2-Stroke Motorized Bicycle Engine Piston Retaining Clips &ndash; Gas Bike Piston Retainer Clips The Piston Retaining Clips help lock in your piston pin within the piston of any 48cc or 66/80cc 2-stroke motorized bike engine kits Installation is simple: with needle nose pliers, remove the retaining clips from within your piston. Once removed, line the point of the pin with the port hole in the piston. Gently squeeze the retaining clip and slide it in the piston. Assure it is within the piston securing the piston pin, and you're ready to ride