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

S&S Cycle big-bore cylinder and piston kits for Milwaukee-Eight engines that transform a 107" displacement to 129" or a 114" to 132" without requiring crankcase machining. Drop-in installation with massive power gains and factory-matching finish.

Features

• Works with stock crankcases — no machine work required
• 4.320 in bore diameter
• Retains stock engine height
• Powder coat finish matches factory finish
• MLS multi-layered steel head gaskets included
• Cubic Inch Cam Cover Badge included
• Made in USA

Specifications

• Brand: S&S Cycle
• Manufacturer Part #: 910-0843A
• Bore Diameter: 4.320 in
• Weight: 29.56 lb
• Category: Engine Components / Piston Sets - Powersports
• Country of Origin: USA

Fitment

Fits Harley-Davidson Milwaukee-Eight engines. Upgrades 107" displacement to 129" or 114" to 132".

Frequently Asked Questions

Do I need to machine my crankcases for this kit?

No — S&S designed this kit to work with stock Harley crankcases. No machine work required.

Will this fit my 107" M8 Harley?

Yes. This kit takes your 107" to 129" displacement.

Will this fit my 114" M8?

Yes. This kit upgrades your 114" to 132" displacement.

What's included in the kit?

Cylinders, pistons, MLS head gaskets, mounting hardware, and a cubic inch cam cover badge.

Does this change my engine height or oil pan?

No — the kit retains stock engine height and works with your existing oil pan and mounting points.