S&S Cycle 4.250" Bolt-On Cylinder & Piston Kit - Harley M8 107ci
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 cylinder and piston kit is a bolt-on solution for 2017 and newer Harley-Davidson Milwaukee-Eight 107 cubic inch engines. It features a 4.250-inch bore and 4.375-inch stroke with an 11:1 compression ratio, designed to boost your engine's displacement and power.
Why riders pick this
- Increases displacement for 2017+ M8 107ci engines
- Features 4.250" bore and 4.375" stroke
- Achieves 11:1 compression ratio with forged pistons
- Bolt-on installation requires no machining
- Wrinkle black finish for a clean, custom look
- Includes all gaskets and hardware for installation
Unleash the true potential of your Milwaukee-Eight 107ci with this S&S Cycle cylinder and piston kit. Engineered for performance, this kit provides a significant upgrade without the need for costly and time-consuming machining. The forged pistons and precisely matched cylinders are built to withstand the demands of increased power, offering a reliable foundation for your performance build.
Performance-Engineered Components
- Features a 4.250-inch bore and 4.375-inch stroke for increased displacement
- Achieves an 11:1 compression ratio for enhanced power output
- Includes durable forged pistons for high-performance applications
- Designed for bolt-on installation with no machining required
- Finished in a wrinkle black for a stealthy look without highlights
- Comes complete with all necessary gaskets and hardware
Boost Your M8's Displacement
This S&S Cycle kit is ideal for riders looking to maximize their M8 107's output. The straightforward bolt-on design means less downtime and a quicker path to more power. Remember to pair this displacement increase with appropriate cam upgrades, a high-flow air intake, and a performance exhaust, all followed by a professional dyno tune to fully realize its potential and ensure optimal engine health.
Specifications
- Brand: S&S Cycle
- Manufacturer Part #: 910-0681A
- Bore x Stroke: 4.250" x 4.375"
- Compression Ratio: 11:1
- Weight: 29.56 lb
- Finish: Wrinkle black without highlight
- Category: Engine Components / Piston Sets - Powersports
Common questions
What is included in this S&S Cycle cylinder and piston kit?
This kit includes the cylinders, piston assemblies, all necessary gaskets, and mounting hardware needed for a complete installation on your Milwaukee-Eight 107ci engine.
Does this kit require any machine work on my engine?
No, this S&S Cycle kit is designed as a bolt-on upgrade and does not require any boring, honing, or other machine shop work to your engine cases or cylinders.
Is this kit suitable for Harley Tri-Glide models?
This kit is generally not recommended for Tri-Glide or other three-wheel Harley-Davidson models. We advise confirming specific fitment for your application.
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 | T14-852155 |
| WEIGHT | 29.56 lb |