The use of these 3 7/8" bore pistons with stock 4" stroke enlarges the capacity of your Twin Cam engine from 88 to 95CI with the use of bored to size stock cylinders. Available with 9:1 or 9.5:1 compression ratio, which can be used with the stock ignition on both carburetor and EFI equipped models, or domed with 10.5:1 compression ratio, which requires the use of a High-Performance ignition system, such as our Dyna ignition ZPN 730588. These Big Bore kits contain a pair of Wiseco forged pistons, a Hastings ring set, chrome wrist pins, circlips and a top end gasket kit. Ring sets are separately available.