Kb Pistons Super Duty 4.250" Bore Piston Pair - Harley Milwaukee-Eight 114/117
About Kb Pistons
KB Performance Pistons builds hypereutectic and forged pistons for American V-twin engines, and is a long-standing choice for big-bore and stock-replacement rebuilds where budget and durability both matter.
These KB Pistons Super Duty pistons are purpose-built for Milwaukee-Eight engines, making them a prime choice for riders pushing their M8 114 or 117 to bigger displacement. Engineered to withstand the demands of high-performance V-twin applications, these pistons are ready for serious power.
Why riders pick this
- Designed for 4.250" bore Milwaukee-Eight engines
- Ideal for 114/117 to 128"+ displacement builds
- Anodized crown and skirt coating for durability
- Includes premium Hastings rings, wrist pins, and locks
- Optimized compression ratio for performance applications
When you're building out a Milwaukee-Eight for maximum output, the foundation matters. These KB Pistons Super Duty pistons are designed to handle the increased power and heat of big-bore M8 builds. With a 4.250" bore, they're suited for displacement upgrades from 114"/117" up to 128" and beyond, giving you the robust internals needed for a reliable, high-horsepower engine.
Engineered for Extreme Durability
- Anodized crown and top ring groove for superior heat resistance
- Line2Line abradable skirt coating ensures a tight, consistent running fit
- Premium Hastings ring package with steel nitride and ductile Napier rings for long life
- Forced wrist pin oiling system enhances lubrication in critical areas
- Valve pockets cut to accommodate 1mm oversized valves
The Core of a Performance Build
These pistons are more than just replacement parts; they're a critical component in any serious Milwaukee-Eight performance build. The flat-top design with a specific dish volume and compression height is optimized for the power goals of a large displacement M8. Paired with a cam swap and a proper dyno tune, these pistons lay the groundwork for a formidable V-twin engine.
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
Common questions
Will these pistons fit my specific Milwaukee-Eight model?
These pistons are designed for Milwaukee-Eight engines with a 4.250" bore, typically used in 114"/117" to 128"+ displacement builds. Please confirm your engine's bore size and intended displacement before ordering.
Do I need any other modifications to install these pistons?
Installing these pistons is part of a larger engine build. It will require cylinder boring/honing and professional assembly. A proper dyno tune will be essential to maximize performance and ensure engine longevity after installation.
Are these pistons sold individually or as a set?
These KB Pistons Super Duty pistons are sold as a pair, including all necessary rings, wrist pins, and locks for both cylinders.
Ordering from Vtwinbikers
- Brand new, sourced through authorized US distribution — never used, never grey-market.
- Not sure it fits? Use Shop by Bike to filter by your year and model, or email us and we will confirm before you order.
- Harley-Davidson and Indian Motorcycle is all we do, so you are talking to people who ride what you ride.
| BRAND | Kb Pistons |
| TYPE | Piston kits & Components |
| SKU | 824-01835 |
| WEIGHT | 2.5 lb |
