Wiseco 4012P4 HD Pan/Shovelhead Forged Piston Kit 3.477 in. Bore 9:1 CR

The Wiseco 4012P4 is a 4 Stroke Forged Series Piston Kit engineered specifically for Harley-Davidson Panhead and Shovelhead V-Twin engines. Featuring a 3.477 in. (88.32 mm) actual bore diameter — a .040 in. oversize over the standard 3.437 in. bore — and a 9:1 compression ratio, this kit is purpose-built to restore or upgrade 74ci Big Twin performance.

Kit Includes:

• Forged aluminum piston(s) — Part No. 4012P4
• Ring set — 3477X (88.32 mm)
• Chromed piston pin — S521 (20.1 mm x 2.598 in.)
• Round wire pin locks — W5731 (Harley 20 mm, per pair)

Key Specifications:

• Actual Bore: 3.477 in. (88.32 mm)
• Oversize: +.040 in.
• Stroke: 3.968 in.
• Displacement: 1,234cc (74ci)
• Compression Ratio: 9:1
• Dome Type: Domed
• Dome Volume: +52.0cc
• Intake Valve Pocket Depth: -0.087 in. / Diameter: 2.045 in.
• Exhaust Valve Pocket Depth: -0.089 in. / Diameter: 1.800 in.
• Piston Pin Diameter: 20.1 mm

Key Features:

• Forged from aerospace-grade aluminum — the forging process aligns grain flow for superior strength, impact resistance, and fatigue resistance compared to cast alternatives
• Engineered and manufactured in the USA — designed, forged, and machined in Mentor, OH
• Platform-specific design — optimized piston geometry for the Panhead and Shovelhead engine architecture to maximize horsepower and torque
• Tightest manufacturing tolerances — CNC-machined after forging using 3D design and finite element modeling for optimal fit and performance
• Complete kit — includes piston, rings, pin, and circlips for a straightforward installation

Important Notes:

• This is an oversize piston — cylinder boring or sleeving is required before installation
• Not CARB legal — not for sale or use in California

Wiseco has been manufacturing forged performance pistons since 1941, and their V-Twin line reflects over 80 years of motorsports engineering experience. The 4012P4 is the ideal choice for a high-performance Panhead or Shovelhead rebuild that demands durability and reliable power output.