Kb Pistons Super Duty 4.125" Bore +.020 Flat-Top Piston Set - Harley Milwaukee-Eight 114 to 120
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.
Take your Milwaukee-Eight engine to the next level with the Kb Pistons Super Duty Piston Set. These 4.125" bore, +.020 overbore pistons are engineered for 114 to 120 cubic inch builds, offering maximum durability and a precise fit for your Harley-Davidson.
Why riders pick this
- Designed for Milwaukee-Eight 114 to 120 cubic inch engines
- 4.125" bore with +.020 overbore for rebuilds
- Anodized top ring groove and crown for durability
- Line2Line abradable skirt coating for precise fit
- Includes premium Hastings rings, wrist pins, and locks
When you're building a high-performance Milwaukee-Eight engine, every component matters. The Kb Pistons Super Duty Piston Set is designed for M8 114 to 120 cubic inch engines, featuring a 4.125" bore with a +.020 overbore. This larger size is ideal for maximizing displacement and restoring cylinder integrity during a rebuild. The advanced design ensures tight running clearances and quiet operation, essential for a reliable performance V-twin.
Advanced Engineering for Reliability
- Anodized top ring groove and crown for exceptional wear resistance
- Line2Line abradable skirt coating provides a self-honing, precise fit
- Premium Hastings ring package for superior sealing and reduced friction
- Forced wrist pin oiling enhances lubrication and component longevity
- Flat-top 1.2cc design with optimized compression height
Performance Ready
Each pair of Super Duty pistons comes complete with all necessary rings, wrist pins, and locks, making your engine build process more efficient. These pistons are an excellent choice for riders seeking to improve the durability and power output of their Milwaukee-Eight Touring or Softail, especially when paired with a performance cam and a dyno tune. They are built to handle the demands of aggressive riding.
Specifications
- Brand: KB Pistons
- Manufacturer Part #: KB542LCA.020
- Bore Size: 4.125 inches
- Engine: Milwaukee-Eight (M8)
- Displacement Range: 114 to 120 cubic inches
- Oversize: +.020 inches
- Compression Height: 1.083 inches
- Top Ring Groove: Anodized
- Weight: 2.5 lbs per pair
- Country of Origin: Mexico
- Quantity: Pair (2 pistons)
Common questions
What is the overbore size of these pistons?
These Kb Pistons Super Duty pistons feature a +.020 overbore, designed for Milwaukee-Eight engines from 114 to 120 cubic inches with a 4.125" bore.
Are rings and pins included with the pistons?
Yes, this piston set comes as a complete pair, including premium Hastings rings, wrist pins, and locks for a straightforward installation.
Will my cylinders need machining for these pistons?
Yes, since these are +.020 overbore pistons, your cylinders will need to be bored out to the appropriate size to ensure proper fitment. Always confirm with your engine builder.
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 | 824-01802 |
| WEIGHT | 2.5 lb |
