Cylinder Kit - Monster Big Bore - 100" - Black w/Highlighted Fins - Evolution Big Twin '84-'99 Aerospace-grade all-aluminum cylinders with nickel-silicon-carbide (NSC) electroplated bores No sleeving allows for larger bore sizes NSC-plated cylinders have less frisction for increased horsepower, lower engine temperatures and longer lifespan Includes 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 Made in the USA Will require case boring, which is not recommended on OEM cases '95-earlier; some may require a 4-5/8" stroke crank. Upgraded cylinder studs and head bolts recommended. Replacement gasket sets and piston kits available separately.