Installing the Athena Factory Cylinder Kit on your bike makes it truly race ready and able to compete with the best of the best. Made with nickel-carbide coating, and ported to factory "Works" specs for 2-stroke motorcycles. Comes with a removable bronze dome, allowing for higher compression and anti-detonating features to improve the life of your motorcycle's engine. Uses specially designed high-performance, high anodized power valves. Also uses a specially designed high-performance Cast-lite, flat-top piston, special gaskets and seals which are included with the kit for easy and complete installation. The Athena Factory cylinder kit provides a cylinder bore of 54 mm and a 54.4 mm stroke which adds power without changing the displacement. Note: The Athena Factory Cylinder Kit does NOT include the upper connecting rod needle bearing.