Kb Pistons Super Duty Piston - 4.125" Bore M8 114/117 TO 120" +.020 — Harley-Davidson (2017-2020)

KB Pistons Super Duty pistons for Milwaukee-Eight (M8) engines from 114 to 120 cubic inches, designed for stock and mildly modified builds. Each pair includes rings, wrist pins, and locks for a complete piston assembly ready to install.

Features

• Anodized top ring groove and crown
• Line2Line Abradable skirt coating for zero initial clearance that self-hones for tight, quiet operation
• Round wire wrist pin locks
• Premium Hastings 1.2mm/1.2mm/3.0mm Steel Nitride top ring with Ductile Napier second ring
• Forced wrist pin oiling
• Flat-top design with 1.2cc dish and 1.083" compression height
• Accommodates 1mm oversize valves
• Sold as a pair with all rings and hardware included

Specifications

• Brand: KB Pistons
• Manufacturer Part #: KB542LCA.020
• Bore Size: 4.125 inches
• Engine: Milwaukee-Eight (M8)
• Displacement Range: 114 to 120 cubic inches
• Oversize: +.020 inches
• Compression Height: 1.083 inches
• Top Ring Groove: Anodized
• Weight: 2.5 lbs per pair
• Country of Origin: Mexico
• Quantity: Pair (2 pistons)

Fitment

Fits Milwaukee-Eight (M8) V-twin engines in the 114 to 120 cubic inch displacement range with a 4.125-inch bore.

Frequently Asked Questions

What's included in this piston kit?

Each pair includes two pistons, Hastings steel-nitride top rings, Napier second rings, wrist pins, and round wire locks — everything needed for installation.

Will these pistons work with my 110-inch M8?

These are designed for 114 to 120-inch M8 engines. A 110-inch engine requires a different bore size and piston part number.

What does the Line2Line Abradable coating do?

The coating allows zero initial clearance, then self-hones as the engine runs to achieve a tight, quiet running fit without loose piston slap.

Can I use these in a stock 114-inch M8?

Yes. These pistons work in stock displacement and mildly modified 114 to 120-inch M8 builds. For heavily modified engines, consult KB Pistons about compression ratio and boost compatibility.

Do these accommodate larger valves?

Yes — the pockets are sized for 1mm oversize valves if your cylinder head has been ported or upgraded.