S&S CYCLE SKU: T14-662045

S&S Cycle Cylinder & Piston Kit 4.320 in. Bore - Harley Milwaukee-Eight

$746.95
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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.

Unleash more power from your 2017-and-newer Milwaukee-Eight engine with the S&S Cycle Cylinder & Piston Kit. This kit provides a robust foundation for top-end rebuilds and performance upgrades. Featuring precision-forged construction, it's built to withstand the demands of high-performance V-twin riding.

Why riders pick this

  • For 2017+ Harley Milwaukee-Eight engines
  • Precision-forged construction
  • 4.320-inch bore, 4.375-inch stroke
  • Enhances top-end performance and durability

The S&S Cycle Cylinder & Piston Kit is engineered to elevate the performance of your Harley-Davidson Milwaukee-Eight engine. With a focus on durability and precision, these components are designed to deliver consistent power and reliability. The 4.320-inch bore and 4.375-inch stroke are optimized for the late-model Big Twin platform, making this kit an ideal choice for riders looking to enhance their engine's capabilities.

Built for Milwaukee-Eight Power

  • Designed for 2017 and newer Milwaukee-Eight (M8) engines
  • Features a 4.320-inch bore and 4.375-inch stroke
  • Precision-forged construction for enhanced strength and longevity
  • Ideal for top-end rebuilds and performance enhancements

Foundation for Performance Builds

This S&S Cycle kit provides the core components for a significant engine upgrade. While it's a solid foundation, remember that top-end rebuilds involve detailed engine disassembly and precise assembly. For optimal results and to ensure all components work together seamlessly, professional installation is highly recommended. Always verify the kit contents to confirm if piston rings and gaskets are included or if they need to be purchased separately for your build.

Specifications

  • Brand: S&S Cycle
  • Manufacturer Part #: 920-0150
  • Bore × Stroke: 4.320 in × 4.375 in
  • Weight: 3.22 lb
  • Category: Engine Components / Piston Sets - Powersports

Common questions

Will this fit my pre-2017 Harley Twin Cam engine?

No — this kit is specific to 2017 and newer Milwaukee-Eight (M8) engines. Twin Cam owners need a different S&S Cycle piston and cylinder kit designed for their platform.

Do I need to buy gaskets and rings separately?

Kit contents can vary. Always check the product description or consult S&S Cycle directly to confirm whether rings and gaskets are included or if they need to be purchased separately for your specific build.

Is professional installation required for this kit?

Top-end rebuilds involving cylinder and piston replacement require engine disassembly and precise assembly. Professional installation by an experienced V-twin mechanic is highly recommended to ensure proper function and longevity.

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.
BRANDS&S Cycle
TYPEPiston Sets - Powersports
SKUT14-662045
WEIGHT3.22 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
5★ 7
4★ 1
3★ 0
2★ 0
1★ 0
✓ VERIFIED
Sep 26, 2019

Really nice kit great directions for install and ring gap. Follow the directions and you can't go wrong..

— Anonymous
✓ VERIFIED
Apr 26, 2022

Excellent service and pricing im very satisfied

— Anonymous
✓ VERIFIED
Sep 26, 2019

Better than OEM.. can't go wrong.

— Anonymous
✓ VERIFIED
Mar 30, 2026

Very happy with this kit

Simple, easy kit.

— Joe G
✓ VERIFIED
Mar 29, 2026

SMS makes great aftermarket upgrades

— Ron B
✓ 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.

— Bruce H