Kb Pistons Super Duty 4.250" Bore M8 107-124" 11.8:1 +.005 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 engineered for Harley-Davidson Milwaukee-Eight 107 to 124 cubic inch engines that require a +.005 overbore. This 4.250" bore, 11.8:1 compression kit provides a robust and high-performance solution for your engine build, sold as a complete pair.
Why riders pick this
- For Harley Milwaukee-Eight 107-124 cubic inch engines
- 4.250" bore with +.005 oversize and 11.8:1 compression
- Anodized crown and top ring groove for extreme durability
- Abradable skirt coating for tight, quiet running
- Includes premium rings, wrist pins, and locks
- Valve pockets accommodate 1mm oversize valves
When rebuilding your Milwaukee-Eight engine, choosing the right pistons is critical for both performance and reliability. These KB Super Duty pistons are built to handle higher compression and the demands of aggressive riding. The +.005 oversize is ideal for cylinders that have been bored for cleanup or to achieve a precise, tighter fit during a performance build.
Precision Engineering for M8 Performance
- Anodized crown and top ring groove for exceptional durability and heat resistance
- Line2Line abradable skirt coating ensures tight, quiet running clearances
- Premium Hastings 1.2mm steel nitride top ring and ductile Napier second ring for optimal sealing
- Forced wrist pin oiling enhances lubrication and extends the life of critical components
- Flat-top design with valve pockets accommodating 1mm oversize valves
Upgrade Your Milwaukee-Eight Build
This comprehensive piston kit provides everything you need for a top-end overhaul, including pistons, rings, wrist pins, and locks. Achieve a higher compression ratio for a noticeable increase in power and responsiveness. These pistons are designed for riders who demand the best from their Milwaukee-Eight, offering a blend of advanced technology and reliable performance.
Specifications
- Brand: KB Pistons
- Manufacturer Part #: KB595LCA.005
- UPC: 800745276162
- Bore: 4.250 in
- Engine Size: M8 107–124 cubic inches
- Compression Ratio: 11.8:1
- Compression Height: 1.083 in
- Top Ring Groove: Anodized
- Weight: 2.5 lbs
- Country of Origin: Mexico
- Quantity: Pair (2 pistons)
Common questions
What engine sizes are these pistons designed for?
These KB Pistons Super Duty pistons are designed for Harley-Davidson Milwaukee-Eight (M8) engines ranging from 107 to 124 cubic inches, specifically with a +.005 overbore.
What is the compression ratio of this piston kit?
This kit delivers an 11.8:1 compression ratio, providing a significant boost for performance-oriented M8 builds.
Does this kit include all necessary components for installation?
Yes, this kit comes as a pair of pistons and includes all the necessary rings, wrist pins, and locks for a complete installation.
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 | 824-01833 |
| WEIGHT | 2.5 lb |
| 11.8 | 1 Compression |
