Kb Pistons Super Duty 4.250" Bore M8 107-124" 11.4:1 +.005 Piston Kit - Harley & Indian V-Twin
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.
This KB Pistons Super Duty piston kit is tailored for Milwaukee-Eight Harley-Davidson and Indian Motorcycle big-twin engines, specifically for 107 to 124 cubic inch builds requiring a +.005 overbore. Featuring a 4.250" bore and 11.4:1 compression, this matched pair is ready to elevate your engine's output.
Why riders pick this
- For Harley-Davidson and Indian M8 107-124 cubic inch engines
- 4.250" bore with +.005 oversize and 11.4:1 compression
- Anodized crown and top ring groove for durability
- Abradable skirt coating ensures tight, quiet running
- Includes premium rings, wrist pins, and locks
- Valve pockets accommodate 1mm oversize valves
When rebuilding or upgrading your V-twin, precise components are crucial for optimal performance and longevity. These Super Duty pistons deliver with a focus on durability and efficiency. The +.005 oversize is perfect for cylinders that have seen some wear or are being prepped for a tighter new fit, ensuring your build is precise and robust.
Advanced Piston Technology for V-Twins
- Anodized top ring groove and crown for exceptional wear resistance
- Line2Line Abradable skirt coating for zero initial clearance and quiet operation
- Premium Hastings Steel Nitride top ring and Ductile Napier second ring
- Flat-top design with valve pockets compatible with 1mm oversize valves
- Forced wrist pin oiling to enhance lubrication and reduce friction
Ready for Aggressive Builds
Designed for demanding applications, these pistons provide the foundation for a powerful and reliable engine. The included rings, wrist pins, and locks simplify the assembly process, allowing you to get your bike back on the road or track with confidence. Pair these with a performance cam and a proper dyno tune to unlock the full potential of your Milwaukee-Eight or Indian V-twin.
Specifications
- Brand: KB Pistons
- Manufacturer Part #: KB576LCA.005
- UPC: 800745266958
- Application: M8 engines 107–124 cubic inches
- Bore Size: 4.250 inches
- Compression Height: 1.083 inches
- Top Design: Flat top, 1.2cc bowl
- Quantity: Pair (2 pistons)
- Weight: 2.5 lbs
- Country of Origin: Mexico
Common questions
What does the "+.005" in the description mean?
The "+.005" indicates that these are an oversize piston kit, designed for cylinders that have been bored .005 inches over stock. This is typically done during an engine rebuild to clean up cylinder walls.
Are these pistons suitable for both Harley-Davidson and Indian Motorcycle M8 engines?
Yes, these KB Pistons Super Duty pistons are designed to fit both Harley-Davidson and Indian Motorcycle V-twin big-twin engines with M8 architecture, specifically for 4.250" bore applications.
What is included with the piston kit?
This kit is sold as a matched pair and includes both pistons, premium rings, wrist pins, and round wire 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 | 824-01831 |
| WEIGHT | 2.5 lb |
| 11.4 | 1 Compression |
