This 3-13/16" stroke 7-7/8" diameter flywheel assembly replaces the original flywheels in1991-'99 HD^® 1200cc Sportster^® models. Flywheels are balanced to S&S^® 92-2016 3-1/2" bore pistons. Flywheels are CNC machined from heat-treated, closed die, steel forgings, and are stronger than cast iron or late style steel flywheels. Dynamically balanced and fully assembled with premium quaility S&S^® mainshafts and heavy duty 6.926" connecting rods.