Wiseco K1691 HD Evo Forged Piston Kit Over Bore - 1340 005 3.503

The Wiseco K1691 is a complete forged piston kit designed for the 80 cu. in. (1340cc) Harley-Davidson Evolution Big Twin engine. This kit features a +.005" oversize bore of 3.503", bringing displacement to approximately 1342cc, and is engineered for use with Screamin' Eagle cylinder heads. It includes front piston 4726P05 and rear piston 4727P05, along with pin 3504X, making it a full assembly-ready solution.

Kit Includes:

• Two forged pistons (front: 4726P05 / rear: 4727P05)
• Piston pin (3504X)
• Rings, circlips, and chrome piston pins

Key Features:

• Forged aerospace-grade aluminum construction — high silicon, low expansion alloy for superior strength, reduced weight, improved heat transfer, and longer service life
• +.005" oversize bore (3.503") — ideal for slightly worn cylinders or performance rebuilds requiring minimal overbore
• CNC diamond-turned finish — precision machining ensures a perfect fit with no size variation
• Enlarged valve pockets — provides clearance for larger valves and high-lift camshafts
• Top ring land grooves — reduces detonation and improves top ring sealing performance
• Ream-fit wrist pin holes — ensures perfect geometrical surface for reliable wrist pin fitment
• Compatible with all cylinder bore types — suitable for cast iron, chrome, nikasil, and boron composite cylinder compositions
• Made in the USA — manufactured at Wiseco's state-of-the-art facility in Mentor, Ohio

Cross-reference part numbers: 4726P05 (front piston), 4727P05 (rear piston), 3504X (pin). Companion ring set: S534. Wiseco K1691 is a build-on-demand item — contact Wiseco for lead times and batch minimums.