Wiseco K1669 Forged Piston Kit 80ci Evolution Big Twin 1340cc +0.040" 3.538" Bore 10:1

The Wiseco K1669 is a complete forged piston kit engineered for the Harley-Davidson 80-cubic-inch (1340cc) Evolution Big Twin engine. Designed as a +0.040" oversize rebuild solution, this kit delivers a 3.538" actual bore diameter and a 10:1 compression ratio, making it an ideal choice for engine rebuilds, overbore projects, and high-performance top-end refreshes.

Wiseco pistons are forged from high-silicon, low-expansion aluminum alloy, a material choice that provides superior tensile strength, reduced reciprocating weight, and improved heat transfer compared to cast alternatives. Each piston features a diamond-turned CNC finish that guarantees precise sizing with zero variation, ensuring a confident fit in cast iron, chrome, Nikasil, and boron composite cylinder bore compositions.

Kit Contents:

• 1x Wiseco 4724P4 Front Forged Piston (10:1 compression)
• 1x Wiseco 4725P4 Rear Forged Piston (10:1 compression)
• 2x Wiseco 3537X Piston Ring Sets (X-Ring package)
• 2x Wiseco S534 Chrome Wrist Pins
• 2x Wiseco W5731 Round Wire Wrist Pin Locks / Circlips (pair)

Key Specifications:

• Oversize: +0.040" (standard bore 3.498", actual bore 3.538")
• Compression Ratio: 10:1
• Ring Package: 0.062" top ring, 0.062" compression ring, 0.158" oil ring
• Intake Valve Pocket Diameter: 2.080"
• Exhaust Valve Pocket Diameter: 1.740"
• Wrist Pin: Wiseco S534
• Displacement: 1340cc (80 ci)
• Made in the USA

Wiseco's oversize piston range extends the service life of cast iron lined cylinders. For chrome, Nikasil, and boron composite bores, these pistons can be used after cylinder resleeving with compatible replacement sleeves. Whether you're rebuilding a worn top end or chasing more performance, the K1669 delivers the precision and durability Wiseco is known for across decades of powersports racing and street riding.