158cc high performance cylinder kit for 125cc & 150cc GY6 scooter engines, by manufacturer NCY A high quality kit that can be used to upgrade 125cc & 150cc GY6 scooter engines to 158cc that is ideal for modern city and highway riding 30 Day Warranty Description 158cc high performance cylinder kit for 125cc 150cc GY6 scooter engines, by manufacturer NCY. A high quality kit that can be used to upgrade 125cc 150cc GY6 scooter engines to 158cc that is ideal for modern city and highway riding. Easy bolt on installation. Upgrading your 150cc GY6 has never been more convenient with this easy to install upgrade kit. This scooter upgrade kit increases your engine bore size to 158cc with a 61 mm piston diameter. Includes an aluminum cylinder with piston, rings, and gaskets. You will see a direct increase in performance after installation with both enhanced low end acceleration and improved top speed. Combine this kit with a high performance carburetor and exhaust for an even larger boost in performance. Specifications Displacement: 158cc Piston Diameter: 61 mm