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 M8 engines, featuring a 4.250" bore and 4.375" stroke with 11:1 compression ratio. Bolt-on design requires no machining, and includes all gaskets and hardware needed for installation.

Features

• 4.250" bore / 4.375" stroke
• 11:1 compression ratio
• Forged pistons
• Bolt-on installation — no machining required
• Wrinkle black finish without highlight
• Gaskets and hardware included

Specifications

• Brand: S&S Cycle
• Manufacturer Part #: 910-0681A
• Bore x Stroke: 4.250" x 4.375"
• Compression Ratio: 11:1
• Weight: 29.56 lb
• Finish: Wrinkle black without highlight
• Category: Engine Components / Piston Sets - Powersports

Fitment

Fits 2017 and newer Harley-Davidson M8 models with 107 cubic inches. Not recommended for Tri-Glide or other three-wheel models.

Frequently Asked Questions

What's included in this kit?

The cylinder, piston assembly, gaskets, and all mounting hardware needed for installation.

Does this require any machine work?

No — this is a bolt-on kit that does not require boring, honing, or other engine machine shop work.

Will this fit my Tri-Glide?

No — S&S does not recommend this kit for three-wheel models like the Tri-Glide.

What compression ratio does this give me?

This kit delivers an 11:1 compression ratio, which boosts power on pump gas without requiring exotic fuel.

What models does this fit?

All 2017+ Harley-Davidson M8 models with 107 cubic inches. Verify your engine displacement before ordering.