Flywheels for HD® Milwaukee-Eight® Models

The Flywheels are the heart of any performance engine and S&S Cycle has been perfecting the art for over six decades. Stronger, more durable, and trued to a spec others can only dream of, our new crankshaft assemblies for the Milwaukee-Eight® platform are the best of the best to build your high performance engine around.

  • Available in 4 3/8", 4 1/2" & 4 5/8" Stroke
  • Available with or without Balancer Gear
  • Heat Treated 4140 Material is harder & more than twice as strong as stock
  • Stronger assembly eliminates need to weld crankpin
  • S&S High Strength Connecting Rods are designed with Finite Element Analysis to eliminate weak spots and handle more power!
  • Available with either full width or tapered wristpin connecting rods
  • Perfect for Gear Drive Cams
  • Consistent balance & precision machining
  • Capable of higher RPM–More available power!
Tapered Connecting Rods
2020-04-30 (1)
Full Width Connecting Rods

Flywheel Assemblies for 2017-2020 M8 Models

DisplacementStrokeComp RatioBalanced to Total
Piston Weight (gms)
Rod Wristpin End StyleBalancer GearPart#


(with S&S cylinders & pistons)

4 3/8"10.81213FullYes320-0604


(with S&S cylinders & pistons)

4 1/2"10.81213FullYes320-0603


(with S&S cylinders & pistons)

4 5/8"10.81213FullYes320-0605