Flying Horse 66cc/80cc 2-Stroke Motorized Bicycle Engine Piston Ring Set &ndash; Gas Bike Piston Ring Replacements The 66/80cc Piston Ring Set includes both the piston rings needed for your 66/80cc motorized bike engine To install begin with uninstalling your cylinder assembly to expose the piston. Gently stretch the existing piston rings and maneuver them off the piston. With the rounded end of the piston rings facing down, gently stretch the new piston rings over the piston and slide them in to the grooves of the piston. Reinstall the cylinder assembly and you're ready to ride Note: Be sure that the pins in the piston ring grooves are centered within the grooved portion of the piston ring Compatible with most bike engine kit motors, including Flying Horse, Mega Motors, Power King, Grubee, Stinger, and many others