S&S Cycle Flywheels — Harley-Davidson Electra Glide, Softail Heritage Classic, Electra Glide Classic (1955-2026)

S&S Cycle flywheels for Harley-Davidson, engineered with finite element analysis and heat-treated 4140 material to deliver strength and durability that handles sustained high-RPM power. Built as the foundation of a true performance engine, trued to precision specs and balanced for stock piston weight.

Features

• Heat-treated 4140 material — over 2x stronger than stock
• Finite element analysis design eliminates weak spots
• Tapered wristpin compatible with stock pistons
• 4.5-inch stroke (fits 114 or 128 cubic inch engines)
• Balanced for stock 1060g piston weight
• Balance gear installed and precision-machined
• Capable of higher RPM without crankpin welding
• Optimized for gear drive cam conversions

Specifications

• Brand: S&S Cycle
• Manufacturer Part #: 320-0598
• Category: Drivetrain / Flywheels
• Weight: 40 lb

Fitment

Fits Harley-Davidson models. Verify engine displacement (114 or 128 cubic inch) and cam drive type before ordering to ensure proper fitment.

Frequently Asked Questions

Will these flywheels work with my stock pistons?

Yes — the tapered wristpin design is compatible with stock Harley pistons and balanced for 1060g piston weight.

Can I use these with a gear-drive cam conversion?

Yes — S&S designed these flywheels with gear drive cams in mind.

Do I need to have the crankpin welded for strength?

No — the stronger 4140 material eliminates the need for crankpin welding, saving machine shop costs.

What stroke length is this?

4.5-inch stroke, available for both 114 and 128 cubic inch configurations.

Are these balanced?

Yes — the balance gear is installed and precision-machined to match stock piston weight.