Kb Pistons Hypereutectic Cast Piston 10.5:1 .005 - Harley Evolution 80ci
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.
Elevate your Evolution 80ci engine's performance with KB Pistons Hypereutectic Cast Pistons. Engineered for riders seeking a boost in compression without sacrificing durability, these pistons are a solid choice for a more aggressive street machine.
Why riders pick this
- 16% silicon hypereutectic alloy for stability
- Low thermal expansion allows tight clearances
- Optimized for 10.5:1 compression ratio
- Reduces engine noise and wear
- Designed for air-cooled Harley Evolution 80ci
These pistons are crafted from a specialized 16% silicon hypereutectic alloy, which provides exceptional thermal stability and minimal expansion. This allows for tighter piston-to-cylinder wall clearances, critical for air-cooled engines, resulting in improved ring seal, reduced blowby, and a quieter, more efficient power delivery.
Performance-Oriented Design
- 16% silicon hypereutectic alloy for reduced thermal expansion
- Designed for tight piston-to-cylinder wall clearance
- Optimal ring seal for improved engine efficiency
- Reduces engine noise and wear in air-cooled applications
- Rated for 10.5:1 compression, suitable for pump fuel
Building for Power and Reliability
With a 10.5:1 compression ratio, these pistons are ideal for Evolution 80ci builds looking to unlock more power while remaining compatible with pump fuel. The .005 oversized bore ensures a precise fit for cylinders that have been reconditioned, providing a fresh sealing surface and maximizing engine longevity. Pair these with a performance cam for a noticeable improvement in throttle response and torque.
Specifications
- Brand: KB Pistons
- Manufacturer Part #: KB266.005
- UPC: 800745061362
- Compression Ratio: 10.5:1
- Engine Displacement: 80 cubic inches (EVO)
- Oversized: .005 in
- Length: 9.6 in
- Width: 4.8 in
- Height: 4.6 in
- Weight: 2.65 lbs
- Country of Origin: Mexico
Common questions
What compression ratio do these pistons support?
These KB Pistons are rated for a 10.5:1 compression ratio, making them suitable for performance builds running on pump fuel.
Will these fit my stock Evolution 80ci cylinders?
These pistons are .005 oversized, meaning your cylinders will need to be bored to this specification for proper fitment. Consult your mechanic or machine shop.
Why are hypereutectic pistons beneficial for air-cooled engines?
The high silicon content in hypereutectic pistons reduces thermal expansion, allowing for tighter piston-to-cylinder clearances that improve ring seal and reduce noise and wear, which is particularly advantageous for air-cooled V-twins.
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 | 824-01013 |
| WEIGHT | 2.65 lb |
| 10.5 | 1 Compression |
