Upgrade your Harley Evolution Big Twin engine with the Revolution Performance RP201-215W Big Bore Cylinder Kit, designed for models from 1984 to 1999. These aerospace-grade, all-aluminum cylinders feature nickel-silicon-carbide (NSC) electroplated bores, which eliminate the need for sleeving and allow for larger bore sizes. The NSC plating reduces friction, resulting in increased horsepower, lower engine temperatures, and a longer engine lifespan. This kit includes a pair of all-aluminum NSC-coated bore cylinders, custom forged pistons with high-tension rings specifically designed for NSC cylinders, wrist pins, circlips, and a head/base gasket set, providing a comprehensive upgrade for your engine. Constructed in the USA, these cylinders require case boring, which is not recommended on OEM cases from 1995 and earlier; some applications may also require a 4-5/8-inch stroke crank. To ensure optimal performance and durability, upgraded cylinder studs and head bolts are recommended. The kit is compatible with various engine configurations but may necessitate some modifications, such as a larger stroke crank, for certain setups. Replacement gasket sets and piston kits are available separately, allowing for further customization and maintenance. Designed for serious motorcycle enthusiasts seeking increased power and reliability, the Revolution Performance RP201-215W Big Bore Cylinder Kit is a high-quality upgrade that enhances your Harley's performance while maintaining durability. The all-aluminum construction combined with advanced NSC plating provides a significant performance advantage over stock components, making it ideal for both street riding and high-performance applications. Proper installation and case boring are essential to ensure maximum benefit from this upgrade, and professional installation is recommended for best results. <b>Features:</b> * Aerospace-grade all-aluminum cylinders with nickel-silicon-carbide (NSC) electroplated bores * No sleeving necessary, allowing for larger bore sizes * NSC plating reduces friction for increased horsepower and lower engine temperatures * Includes pair of aluminum NSC-coated cylinders, forged pistons, high-tension rings, wrist pins, circlips, and gasket set * Made in the USA, requires case boring, and compatible with various engine configurations