S&S Cycle 4.250" x 4.375" .010" Oversize Piston Set - 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.
This S&S Cycle piston set is precision-machined for 2017 and newer Harley-Davidson Milwaukee-Eight (M8) engines, featuring dimensions of 4.250 inches by 4.375 inches with a .010-inch oversize specification. Designed as a direct replacement, these pistons are ideal for stock or mildly modified M8 motors requiring fresh rings and pistons for optimal performance.
Why riders pick this
- 4.250" x 4.375" piston dimensions
- .010" oversize specification
- Designed for 2017+ Milwaukee-Eight engines
- Direct replacement for stock or modified M8s
- High-quality S&S Cycle engineering
When rebuilding or upgrading your 2017+ Milwaukee-Eight engine, using high-quality pistons is paramount for reliability and performance. This S&S Cycle piston set delivers the precision and durability expected from a leader in V-twin performance. The .010-inch oversize specification is perfect for cylinders that have been lightly honed, ensuring a fresh sealing surface and optimal compression. These pistons are engineered to integrate seamlessly into your M8, providing a solid foundation for many miles of riding.
Engineered for M8 Performance and Durability
- Precisely machined to 4.250 in x 4.375 in dimensions
- .010-inch oversize specification for optimal cylinder refresh
- Designed for 2017 and newer Milwaukee-Eight (M8) engines
- Direct replacement for stock or mildly modified M8 motors
- High-quality construction for lasting engine reliability
Crucial for Engine Rebuilds
Installing a new piston set is a critical step in any engine rebuild or performance upgrade. S&S Cycle highly recommends installing new piston rings, wrist pins, and all associated gaskets and oil seals to ensure a proper seal, optimal compression, and maximum longevity. Always consult your service manual and an experienced engine builder to confirm proper clearances and installation procedures for your specific Milwaukee-Eight application.
Specifications
- Brand: S&S Cycle
- Manufacturer Part #: 920-0141
- Piston Oversize: .010 in
- Weight: 3.22 lb
- Category: Engine Components / Piston Sets - Powersports
Common questions
Will these pistons fit my Twin Cam engine?
No, this piston set is specifically engineered for 2017 and newer Harley-Davidson Milwaukee-Eight (M8) engines. Twin Cam pistons have different dimensions and designs and are not compatible.
Do I need new rings and gaskets when installing these pistons?
Yes, S&S Cycle strongly recommends installing new piston rings, wrist pins, gaskets, and oil seals to ensure a proper seal, optimal compression, and long-term reliability for your engine.
Are these pistons designed for a specific bore size?
Yes, these pistons are designed to be used with cylinders that have a 4.250-inch bore, with the .010-inch oversize accounting for minor cylinder wear or honing.
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 | Piston Sets - Powersports |
| SKU | T14-662028 |
| WEIGHT | 3.22 lb |
