S&S Cycle 107″ Replacement Piston Kit For Harley Twin Cam (2006–2017)

Unlock maximum horsepower and torque from your V-Twin engine with the S&S Cycle 107″ Replacement Piston Kit. Designed specifically for 2006 to 2017 Harley-Davidson Twin Cam models (Dyna 2006–2017, Softail & Touring 2007–2017), this premium forged piston kit is the ultimate upgrade for riders seeking a displacement bump from stock 96 CI or 103 CI up to a massive 107 CI without replacing the crankshaft or flywheels.

Whether you are replacing worn pistons in an existing S&S 107″ big bore setup or precision-boring your stock Harley cylinders, S&S Cycle delivers unmatched metallurgy, exact manufacturing tolerances, and race-proven durability.

Key Features & Benefits

• Forged Aluminum Alloy Construction: Engineered to withstand higher thermal expansion, extreme compression loads, and high-RPM stress compared to standard cast pistons.
• Optimized 107″ Big Bore Performance: Designed for a 3.937″ cylinder bore size to maximize engine displacement on a stock 4-3/8″ flywheel stroke.
• Tapered Wrist Pin Ends: Fully compatible with OEM connecting rods featuring tapered wrist pin ends for smooth installation.
• Enhanced Compression Ratio: Yields an ideal ~10.4:1 to 10.6:1 compression ratio with stock cylinder heads for crisp throttle response and broad powerband gains.
• Complete Replacement Package: Includes lightweight forged pistons, premium high-performance piston rings, wrist pins, and keeper circlips.

Engineered for Precision & Maximum Output

S&S Cycle manufactures their 3.937″ big bore pistons to rigorous tolerances. The lightweight forged design reduces reciprocating mass within the crankcase, minimizing engine vibration while allowing the motor to rev more freely. Paired with high-grade piston rings, this kit provides a superior cylinder wall seal, reducing blow-by and oil consumption under hard acceleration.

Model Fitment & Compatibility

This 107″ replacement piston kit is compatible with 2006–2017 Harley-Davidson Big Twin engines equipped with 3.937″ bore cylinders and standard 4-3/8″ stroke flywheels.

Model Family	Model Years	Fitment & Engine Notes
Dyna	2006–2017	Twin Cam 96″ / 103″ engines
Softail	2007–2017	Twin Cam 96″ / 103″ engines
Touring / Bagger	2007–2016	FLH/FLT Street Glide, Road Glide, Road King, Electra Glide

Technical Specifications

• Brand: S&S Cycle
• Engine Type: Harley-Davidson Twin Cam
• Final Displacement: 107 Cubic Inches
• Bore Size: 3.937 Inches (Standard)
• Stroke Compatibility: 4-3/8 Inches (Stock 96″/103″ stroke)
• Piston Material: High-Strength Forged Aluminum
• Includes: 2x Pistons, Ring Sets, Wrist Pins, & Circlips

Frequently Asked Questions (FAQ)

Can I bore my stock 96 CI or 103 CI cylinders to use these 107″ pistons?

Yes! Stock Harley Twin Cam cylinders can be precision-bored and honed to 3.937″ to accommodate this S&S 107″ piston kit. Alternatively, these serve as direct replacement pistons for S&S 107″ Big Bore Cylinder Kits.

Is ECM tuning required after installing this 107″ piston kit?

Yes. Increasing your engine displacement to 107 CI and bumping compression alters air/fuel mixture requirements. An EFI tuner (such as a Dynojet Power Vision or Vance & Hines Fuelpak) is required to calibrate your fuel maps for proper engine cooling and performance.

Do I need to split the crankcase for installation?

No. The 107″ big bore conversion is a bolt-on top-end modification. No crankcase machining or engine removal is necessary.

Transform your Harley Twin Cam into a high-torque street performer. Order the S&S Cycle 107″ Replacement Piston Kit today!