S&S Cycle Power Packs — Harley-Davidson Electra Glide, Softail Heritage Classic, Electra Glide Classic (1955-2026)

S&S Cycle Power Packs are replacement piston sets for Harley-Davidson big-twin and Sportster engines, engineered to increase displacement and compression for added horsepower and torque output. Direct bolt-in fit for stock or modified engines.

Features

• Increased displacement over stock pistons
• S&S Cycle precision engineering
• Direct replacement fitment
• Higher compression ratio

Specifications

• Brand: S&S Cycle
• Manufacturer Part #: 310-1057D
• Category: Engine Components / Piston Sets - Powersports
• Weight: 44.19 lb

Fitment

Fits Harley-Davidson big-twin and Sportster engines. Verify engine year and displacement with S&S Cycle before ordering to ensure correct piston size and pin diameter for your build.

Frequently Asked Questions

Will these pistons fit my stock Harley engine?

Power Packs are engineered as direct replacements for Harley big-twin and Sportster platforms, but confirm your engine year and displacement with S&S before purchase.

Do I need a complete rebuild to install these?

Piston installation requires engine disassembly and typically includes replacing rings and checking clearances. A qualified machine shop or engine builder is strongly recommended.

What kind of power gains can I expect?

Horsepower and torque gains depend on displacement increase, compression ratio, and engine tuning. S&S provides flow specs — dyno results vary by bike and setup.

Are these street-legal?

Pistons themselves are components. Legality depends on local emissions laws and whether the complete engine build meets your jurisdiction's requirements.