This 4-1/4" stroke 8-1/2" diameter flywheel assembly replaces the original flywheels in 1995-'98 EFI big twin engines. Timing notches on the rim of the left flywheel work with the stock crankshaft position sensor. 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 7.440" connecting rods.