Black wrinkle finish cylinders with non-highlighted fins. Kit includes a forged 4.250" big bore piston kit, black wrinkle 4.250" big bore cylinders, 2 multi-Layer-Steel .030" head gaskets, 2 cylinder base gaskets, 4 cylinder dowels and 2 exhaust gaskets.
Works with stock crankcases, case boring is not required. 4-5/8" stroker flywheels are required, these must be purchased separately as 923270 or 923271.
Note: S&S measured 146.62HP and 145TQ with a 590 cam, CNC heads, Big Bore throttle body and a high flow Stealth air cleaner kit.
Note: Fully assembled 4-5/8" stroke stroker flywheel assemblies are required for installation of this big bore kit. Available as 923270 (with balancer gear installed) or 923271 (without balancer gear). Both come with full width wrist pin connecting rods, which is required for S&S pistons.
Note: S&S 576972 extra strong head bolt kit or similar must be purchased separately. Note: Tuning of fuel injection and ignition is required.
Note: S&S does not advise this kit for use on any Tri-Glide or other three wheelers, including conversions, due to the lugging nature of these bikes.
Fits: > 2018-2021 Harley Davidson Softail; 17-21 Touring (excl. trikes)
