Kb Pistons Super Duty Piston - 4.125" Bore M8 114/117 TO 120" +.010 — Harley-Davidson (2017-2020)

KB Pistons Super Duty piston set for Milwaukee-Eight engines with 4.125" bore, designed for 114cc to 120cc displacement builds up to +.010" overbore. Each pair features anodized grooves, Line2Line abradable skirt coating, and premium Hastels ring package for tight, quiet running clearance.

Features

• Anodized top ring groove and crown
• Line2Line abradable skirt coating (.003" total thickness) for zero initial fit
• Round wire wrist pin locks
• Premium Hastings 1.2mm top ring with Steel Nitride, Ductile Napier second ring
• Forced wrist pin oiling
• Flat-top design with 1.2cc dish, 1.083" compression height
• Rings, wrist pins, and locks included
• Sold as a pair

Specifications

• Brand: KB Pistons
• Manufacturer Part #: KB542LCA.010
• Bore Size: 4.125"
• Overbore: +.010"
• Engine Size: 114cc to 120cc M8
• Compression Height: 1.083"
• Dish Volume: 1.2cc flat-top
• Length: 6 in
• Width: 5 in
• Height: 5 in
• Weight: 2.5 lbs
• Country of Origin: Mexico

Fitment

Fits Harley-Davidson Milwaukee-Eight (M8) engines in the 114cc to 120cc displacement range with 4.125" bore and +.010" overbore.

Frequently Asked Questions

What's included with this piston set?

A pair of pistons plus all rings (top and second), wrist pins, and wire locks — everything needed for installation.

What engine sizes do these fit?

114cc to 120cc Milwaukee-Eight builds on 4.125" bore with +.010" overbore.

Why does the skirt coating say 'zero initial fit'?

Line2Line abradable coating is applied at .003" total thickness and hones itself during initial break-in, creating a tight, quiet running clearance over time rather than out-of-the-box.

Can I use 1mm oversize valves with these pistons?

Yes — the valve pockets are sized to accommodate 1mm oversize valves without interference.

Do these pistons require a tuner or other modifications?

Piston selection depends on your entire build spec. Consult your engine builder or KB Pistons tech support to confirm this set matches your compression ratio and displacement targets.