S&S Cycle 4-5/8" Stroke Flywheels - Harley Milwaukee-Eight
About S&S Cycle
S&S Cycle has built American V-twin performance parts in Viola, Wisconsin since 1958 — flywheels, carburetors, cams, cylinder heads and complete crate engines. When a Harley owner talks about a 124, a 128 or a 131 build, they are usually talking about S&S. Few names carry more weight with engine builders in this space.
Lay the groundwork for an unshakeable Milwaukee-Eight engine with S&S Cycle Flywheels. These flywheels are the backbone of any high-performance M8 build, crafted from heat-treated 4140 material that's twice as strong as stock. Designed to handle elevated RPM and significant power output, they maintain strict balance tolerances for a smooth, powerful ride.
Why riders pick this
- Heat-treated 4140 material for extreme strength
- Full-width wristpin design for durability
- Balanced for S&S 1213g performance pistons
- Compatible with S&S 131 cubic inch kits
- Gear drive cam ready with pre-installed balance gear
When you're pushing the limits of your Milwaukee-Eight, stock flywheels simply won't cut it. S&S Cycle Flywheels provide the robust foundation needed for extreme performance M8 engines. Engineered with precision machining and a full-width wristpin design, these flywheels are built to endure the stresses of increased horsepower and torque. They are carefully balanced for use with S&S performance pistons, ensuring a harmonious and powerful rotating assembly.
Engineered for Extreme M8 Performance
- Constructed from heat-treated 4140 material for superior strength
- Features a full-width wristpin design for enhanced durability
- Precisely balanced for S&S 1213g performance pistons
- Compatible with S&S 131 cubic inch kits for ultimate displacement
- Gear drive cam ready with a pre-installed balance gear
The Core of a Performance M8
These S&S flywheels are not just replacement parts; they are a critical upgrade for any rider serious about building a high-output Milwaukee-Eight. Their inherent strength and precision balancing minimize vibration and maximize power transfer, making them ideal for aggressive riding and high-stress applications. Pair them with S&S Performance Pistons to unlock the full potential of your M8 powerplant.
Specifications
- Brand: S&S Cycle
- Manufacturer Part #: 320-0605
- Category: Drivetrain / Flywheels
- Weight: 40 lb
Common questions
Do I need S&S pistons to use these flywheels?
Yes, these S&S Cycle flywheels feature a full-width wristpin design that requires S&S Performance Pistons (specifically 1213g weight) for correct fitment and proper engine balance.
What stroke are these flywheels designed for?
These S&S Cycle flywheels are built with a 4-5/8 inch stroke, making them compatible with S&S 131 cubic inch kits and other high-performance M8 builds.
Are these flywheels compatible with gear drive cams?
Yes, these flywheels come with a balance gear pre-installed, making them ready for a gear drive cam setup in your Milwaukee-Eight engine.
Ordering from Vtwinbikers
- Brand new, sourced through authorized US distribution — never used, never grey-market.
- Not sure it fits? Use Shop by Bike to filter by your year and model, or email us and we will confirm before you order.
- Harley-Davidson and Indian Motorcycle is all we do, so you are talking to people who ride what you ride.
| BRAND | S&S Cycle |
| TYPE | Flywheels |
| SKU | T14-662051 |
| WEIGHT | 40.0 lb |
