Kb Pistons Super Duty 4.250" Bore M8 114-128" 11.7:1 Standard Piston Kit - Harley Milwaukee-Eight
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.
The KB Pistons Super Duty piston kit is specifically engineered for Harley-Davidson Milwaukee-Eight big-bore engines, supporting builds from 114 to 128 cubic inches. This 4.250" bore, 11.7:1 compression standard size kit provides the foundation for serious street performance or mild boost applications.
Why riders pick this
- Designed for Harley Milwaukee-Eight 114-128 cubic inch engines
- 4.250" bore with 11.7:1 compression ratio
- Anodized crown and top ring groove for extreme durability
- Abradable skirt coating for tight, quiet running clearance
- Includes premium rings, wrist pins, and locks
- Accommodates 1mm oversize valves
When you're pushing the limits of your Milwaukee-Eight, you need pistons that can handle the power. These KB Super Duty pistons are built with advanced features to ensure durability and optimal performance in high-displacement M8 engines. Designed for a standard bore, they offer a direct fit for many 114-128 cubic inch projects, ready for aggressive riding.
Robust Construction for Big-Bore M8s
- Anodized top ring groove and crown for superior strength and heat dissipation
- Line2Line abradable skirt coating ensures zero initial clearance and quiet, self-honing operation
- Premium Hastings 1.2mm steel nitride top ring and ductile Napier second ring for excellent sealing
- Forced wrist pin oiling enhances lubrication and extends the life of critical components
- Flat-top design with valve pockets accommodating 1mm oversize valves
Power and Reliability for Your Build
This piston kit is a critical upgrade for any performance-focused Milwaukee-Eight build. The included rings, wrist pins, and locks provide a complete and straightforward installation, allowing you to get your high-horsepower M8 back on the road. Pair these pistons with a performance cam and a precise dyno tune to unleash the full potential of your big-bore engine.
Specifications
- Brand: KB Pistons
- Manufacturer Part #: KB596LCA.STD
- UPC: 800745276186
- Bore: 4.250 in
- Engine: Milwaukee-Eight (M8) 114/117 to 128 cu in
- Compression Ratio: 11.7:1
- Compression Height: 1.083 in
- Weight: 2.5 lbs per pair
- Country of Origin: Mexico
Common questions
What Milwaukee-Eight engine sizes are these pistons compatible with?
These KB Pistons Super Duty pistons are designed for Harley-Davidson Milwaukee-Eight (M8) engines ranging from 114 cubic inches through 128 cubic inches, with a 4.250 inch bore.
What compression ratio do these pistons offer?
This piston kit provides an 11.7:1 compression ratio, suitable for performance street builds and mild boost applications in big-bore M8 engines.
Are the necessary rings and pins included with this piston kit?
Yes, this kit is sold as a pair and includes all the necessary premium rings, wrist pins, and round wire locks for a complete engine build.
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 | 824-01834 |
| WEIGHT | 2.5 lb |
| 11.7 | 1 Compression |
