Kb Pistons Super Duty Piston - 4.250" Bore M8 114/117 TO 128"+.005 11.7:1 — Harley-Davidson (2017-2021)

KB Pistons Super Duty piston pair for Milwaukee-Eight (M8) engines at 4.250" bore, engineered for displacement builds from 114cc to 128cc+ with 11.7:1 compression ratio. Features anodized crown, Line2Line abradable skirt coating, and premium Hastings ring package for durability in high-performance applications.

Features

• Anodized top ring groove and crown
• Line2Line abradable skirt coating (.003" thickness) for zero initial clearance and tight running fit
• Round wire wrist pin locks
• Premium Hastings 1.2mm top ring with Steel Nitride coating and Ductile Napier second ring
• Forced wrist pin oiling system
• Flat-top design with 1.2cc dish and 1.083" compression height
• Valve pockets cut for 1mm oversize valves
• All rings, wrist pins, and locks included
• Sold as a pair

Specifications

• Brand: KB Pistons
• Manufacturer Part #: KB596LCA.005
• UPC: 800745276179
• Bore Size: 4.250"
• Compression Ratio: 11.7:1
• Compression Height: 1.083"
• Dish Volume: 1.2cc
• Quantity: Pair (2 pistons)
• Engine Platform: M8 (Milwaukee-Eight)
• Weight: 2.5 lbs
• Country of Origin: Mexico

Fitment

Designed for Harley-Davidson Milwaukee-Eight (M8) engines at 4.250" bore. Suitable for displacement builds from 114cc to 128cc+.

Frequently Asked Questions

Do these pistons come with rings and wrist pins?

Yes — all Hastings rings, wrist pins, and round wire locks are included in the pair.

What is the Line2Line abradable skirt coating?

A .003" thick coating that starts with zero clearance and self-hones during break-in to create a tight, quiet running fit.

Can these handle oversized valves?

Yes — the valve pockets are cut to accommodate 1mm oversize valves on M8 heads.

Are these street-legal for my Harley?

These are performance-grade pistons designed for high-displacement builds. Verify your local emissions and noise regulations before installation, especially if combined with other modifications.

What compression ratio do these run?

11.7:1 compression ratio, suitable for premium 91-93 octane fuel in most M8 applications.