This 4-1/8" bore cylinder and piston kit replaces the cylinders and pistons on early production S&S T124 engines for 1999-'06 big twins. The kit contains S&S 4-1/8" bore cylinders, forged pistons, rings, wrist pins, head and base gaskets. Pistons are flat topped design intended for use with S&S Super Stock cylinder heads. The cylinders are machined with the S&S bolt pattern and are intended for use in S&S crankcases used in early S&S T124 engines. Designed for 4-1/8" stroke flywheels, resulting in 124" displacement. Cylinder finish is a durable wrinkle black powder coat. For best performance, appropriate camshafts, performance air cleaner, performance exhaust and fuel system tuning are required.