Wiseco K1661 V-Twin 1200 Evo Sportster Forged Piston Kit +.010" 9:1 Compression

The Wiseco K1661 is a complete forged piston kit designed for Harley-Davidson 1200cc Evo Sportster engines through 2003. This +.010" oversize kit delivers a 3.508" actual bore, 1207cc displacement, and a 9:1 compression ratio with a flat-top piston design — making it a reliable choice for engine rebuilds requiring precision-fit components without cylinder head modifications.

Each kit is forged from high-silicon, low-expansion aluminum alloy, providing superior strength, reduced reciprocating weight, improved heat transfer, and extended service life compared to cast alternatives. A diamond-turned, CNC-machined finish ensures consistent sizing and a precision fit across all supported cylinder bore compositions, including cast iron, chrome, Nikasil, and boron composite.

Kit Includes:

• 2 forged flat-top pistons with ArmorGlide™ coated skirts
• X-Ring package: 0.062" top ring, 0.062" compression ring, and 0.158" oil ring
• Chrome piston pins (S530 — 20.1mm x 2.200")
• Round wire pin locks / circlips

Key Specifications:

• Bore (Standard): 3.498" | Bore (Actual): 3.508" | Oversize: +0.010"
• Stroke: 3.812" | Displacement: 1207cc | Engine Type: 73ci
• Compression Ratio: 9:1 | Dome Type: Flat Top | Dome Volume: -2.8cc
• Valve Pocket Diameter (Intake & Exhaust): 2.100"
• Piston Pin: 20.1mm | No cylinder head modification required
• Ring Set: 3507X (89.01mm)

Wiseco's oversize piston range helps extend the life of cast iron lined cylinders. Where chrome, Nikasil, or boron composite cylinders are used, replacement sleeves can be installed to accept Wiseco oversize pistons. All Wiseco V-Twin piston kits are proudly manufactured in the USA.