Wiseco 4722P4 Forged Piston Kit 1340 Evo Big Twin 3.538in Bore 8.5:1 Compression .040 Over

The Wiseco 4722P4 is a forged aluminum piston kit engineered specifically for the Harley-Davidson 1340cc Evolution Big Twin engine. This is a .040 over (3537X) kit featuring a flat-top piston design with an 8.5:1 compression ratio, making it an excellent choice for reliable rebuilds and mild performance upgrades.

Each kit is engineered, forged, and machined in the USA at Wiseco's facility in Mentor, OH. Starting with aerospace-grade aluminum, the forging process aligns the grain flow of the alloy for a product that delivers superior resistance to impact, fatigue, and tensile stress — characteristics that cast pistons simply cannot match.

Key Features:

• Forged from high-silicon, low-expansion aluminum alloy for superior strength, reduced weight, and improved heat transfer
• Flat-top piston design with 8.5:1 compression ratio — ideal for stock and mild performance builds
• 3.538 in. (3537X) bore diameter — .040 over standard bore of 3.498 in.
• 4.250 in. stroke with 7.440 in. rod length
• Floating wrist pin style for reduced friction and improved reliability
• Diamond-turned CNC finish ensures precise sizing with no variation — compatible with cast iron, chrome, Nikasil, and boron composite cylinder bores
• Kit includes: forged piston, rings, piston pin, and circlips
• Compatible with models featuring Screamin' Eagle cylinder heads
• Oversize pistons require cylinder re-sleeving — compatible with replacement sleeves for chrome, Nikasil, and boron composite cylinders

Wiseco V-Twin piston kits are designed and built specifically for each engine platform, optimizing performance and durability whether you're doing a reliable stock rebuild or building for all-out performance.