Give your GY6 based scooter some serious power with this bolt on 171.3cc kit for most GY6 125/150cc engines. As far as we know, this is the only 61mm cylinder kit for the GY6 engine that exists in the US. With most 61mm cylinder kits, you have to cut the engine cases in some way to make it fit (Outer Cylinder Skirt Diameter: 65mm). Not so with this kit (Outer Cylinder Skirt Diameter: 62.9mm).
It also has a light weight cut-down piston to increase performance even more. It’s highly recommended to jet this kit significantly rich because of its high performance capability. To maximize performance and efficiency, it’s recommended to get our 61mm big valve head as well.