S&S Cycle Cylinder & Piston Kits — Harley-Davidson Street Glide, Softail Fat Boy 114, Road King Special (2017-2026)

S&S Cycle cylinder and piston kit for 2017+ Harley Milwaukee-Eight engines, increasing bore to 4.320 inches for significant displacement and power gain. Installs into stock crankcases without machine work, retaining factory engine height and aesthetics.

Features

• 4.320 in. bore increase
• Works with stock crankcases — no machine work required
• Wrinkle black powder coat finish
• Multi-layered steel (MLS) head gaskets included
• Cubic inch cam cover badge included
• Retains stock engine height
• Made in USA

Specifications

• Brand: S&S Cycle
• Manufacturer Part #: 910-0849A
• Bore: 4.320 in.
• Stroke: 4.625 in.
• Weight: 29.56 lb
• Finish: Wrinkle black
• Category: Engine Components / Piston Sets - Powersports

Fitment

Fits 2017 and newer Harley-Davidson models with Milwaukee-Eight (M8) engines.

Frequently Asked Questions

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

No — this kit is engineered specifically for 2017+ Milwaukee-Eight engines. Twin Cam engines require a different S&S Cycle kit.

Do I need to have my crankcases machined?

No. This kit is designed to work with stock crankcases without any machine work required.

What displacement does this increase the engine to?

The 4.320 in. bore and 4.625 in. stroke combination increases total cubic inches significantly over stock M8 displacement. S&S publishes the final cc/ci figure in their spec sheet.

What gaskets are included?

Multi-layered steel (MLS) head gaskets are included with the kit for a reliable seal.

Does it come with the cam cover badge?

Yes — a cubic inch cam cover badge is included so riders can display the displacement increase.