Give your GY6 based scooter some serious power with this BOLT ON (That’s right BOLT ON!) 171.3cc kit for most GY6 125/150 engines. As far as we know, this is the only 61 mm 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. It also has a light weight cut down piston to increase performance even more. Its highly recommended to jet this kit significantly rich because of it high performance capability. In addition, its recommended to get our 61mm big valve head as well. Some stock heads will not fit.
Have a look at our Decompression Tube Assembly which replaces your dipstick and allows excess crank case pressure to be released. Good idea to install one of these alongside any cylinder kit upgrade.