✓ VERIFIED
Sep 26, 2019
Really nice kit great directions for install and ring gap. Follow the directions and you can't go wrong..
Image coming soon
S&S CYCLE
SKU: T14-852168
S&S Cycle 4.320" Big Bore Cylinder & Piston Kit Black Granite - Harley M8
$1,643.95
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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.
Boost your 2017-later Harley-Davidson Milwaukee-Eight engine's displacement and power with the S&S Cycle 4.320-inch big bore cylinder and piston kit. Featuring a Black Granite powder coat finish, this kit bolts directly onto stock crankcases without the need for any machining.
Why riders pick this
- 4.320-inch bore for significant displacement increase
- Works with stock crankcases, no machining needed
- Black Granite finish with highlights
- Includes MLS head gaskets
- Retains stock engine height
- Comes with Cubic Inch cam cover badge
The S&S Cycle 4.320-inch bore cylinder and piston kit is designed for Milwaukee-Eight owners who want a substantial power increase with a clean, factory-matched aesthetic. This kit offers a significant displacement boost, translating to more horsepower and torque for your V-twin. The Black Granite powder coat finish, complete with matching highlights, ensures your upgraded engine looks as good as it performs, all while maintaining the stock engine height.
Performance and Style Combined
- 4.320-inch bore provides a significant increase in displacement
- Works with stock crankcases, requiring no machine work for installation
- Black Granite powder coat finish with highlights matches factory appearance
- Includes MLS (Multi-Layered Steel) head gaskets for a durable seal
- Retains stock engine height for a seamless fit in your frame
- Comes with a Cubic Inch cam cover badge to denote the upgrade
Straightforward Power Upgrade
This S&S Cycle big bore kit simplifies the process of upgrading your Milwaukee-Eight, allowing for a direct bolt-on installation. The careful design ensures you get a robust performance increase without the complexities often associated with engine modifications. To fully capitalize on the increased displacement and power, consider pairing this kit with a performance cam and a custom dyno tune. It's an ideal choice for riders building a high-performance bagger or Softail.
Specifications
- Brand: S&S Cycle
- Manufacturer Part #: 910-0847A
- Bore: 4.320 in.
- Finish: Black Granite with highlight
- Weight: 29.75 lb
- Category: Engine Components / Piston Sets - Powersports
Common questions
Will this S&S Cycle kit work on my stock M8 crankcase without machining?
Yes, this kit is specifically engineered to bolt directly onto your factory Milwaukee-Eight crankcase with no modifications or machine work required.
Will this big bore kit require engine tuning after installation?
Yes, any significant engine modification like a big bore kit will require a proper dyno tune to optimize fuel delivery and ignition timing for the new displacement and ensure peak performance and reliability.
What is the finish of these cylinders?
The cylinders feature a Black Granite powder coat finish with matching highlights, designed to blend seamlessly with your factory Milwaukee-Eight engine components.
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 | T14-852168 |
| WEIGHT | 29.75 lb |
Please contact us to confirm fitment for your specific motorcycle, or check the product title for compatibility notes.
CUSTOMER REVIEWS
4.88
8 RATINGS
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✓ VERIFIED
Apr 26, 2022
Excellent service and pricing im very satisfied
✓ VERIFIED
Sep 26, 2019
Better than OEM.. can't go wrong.
✓ VERIFIED
Mar 30, 2026
Very happy with this kit
Simple, easy kit.
✓ VERIFIED
Mar 29, 2026
SMS makes great aftermarket upgrades
✓ VERIFIED
Oct 24, 2025
👍👍 For fast delivery
Parts came just like as expected. They look great! Can't wait to install these bad boys along with a few other parts.