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

S&S Cycle piston set for 2017 and newer Harley-Davidson Milwaukee-Eight (M8) engines, featuring a 4.250 in bore with .010 in oversized pins. Direct replacement for stock pistons or upgrade component for higher-displacement custom builds.

Features

• 4.250 in bore x 4.625 in stroke
• 0.010 in oversized pins
• Direct M8 fitment
• Engine upgrade or stock replacement

Specifications

• Brand: S&S Cycle
• Manufacturer Part #: 920-0148
• Bore Size: 4.250 in
• Stroke: 4.625 in
• Oversized: 0.010 in
• Weight: 3.22 lb
• Category: Engine Components / Piston Sets - Powersports

Fitment

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

Frequently Asked Questions

Will these fit my 2017+ M8 Harley?

Yes — these pistons are engineered specifically for 2017 and newer Milwaukee-Eight engines with a 4.250 in bore.

Do I need a rebore if I'm running stock bore?

These are .010 in oversized, so your cylinders must be bored and honed to 4.250 in diameter before installation.

Can I use these with my stock cylinders?

No — stock cylinders are not sized for .010 in oversized pistons. Professional cylinder boring is required.

What's included in the kit?

The piston set only. Rings, pins, and circlips are not included — verify these separately for your build.