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-Davidson Milwaukee-Eight engines, featuring 4.250-inch bore pistons in .010-inch oversized configuration. Increases engine displacement and compression for added horsepower and torque on stock M8 powerplants.

Features

• 4.250 in bore x 4.500 in stroke
• 0.010 in oversized configuration
• Designed for 2017+ Milwaukee-Eight (M8) engines
• Increases displacement and compression

Specifications

• Brand: S&S Cycle
• Manufacturer Part #: 920-0142
• Bore x Stroke: 4.250 in x 4.500 in
• Oversizing: 0.010 in
• Category: Engine Components / Piston Sets - Powersports
• Weight: 3.22 lb

Fitment

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

Frequently Asked Questions

Will this fit my Twin Cam engine?

No — this kit is designed exclusively for 2017+ Milwaukee-Eight (M8) engines. Twin Cam models require a different S&S piston kit.

What kind of displacement increase can I expect?

The 0.010-inch overbore increases total engine displacement compared to stock M8, with exact gains depending on your base engine configuration.

Do I need a tuner with this kit?

A fuel and ignition tuner or ECM flash is strongly recommended to optimize performance and fuel mapping with the increased compression and displacement.

Is professional installation required?

Yes — piston and cylinder installation requires engine disassembly and machine work. Professional installation by a qualified Harley or Indian technician is essential.