Fuel Moto 128” Big Bore Kit – Milwaukee-Eight (M8 114 / 117)
Unlock serious torque and horsepower from your Milwaukee-Eight with the Fuel Moto 128” Big Bore Kit. Designed as a true bolt-on upgrade, this piston and cylinder kit transforms your stock 114” or 117” engine into a 128” performance setup—without the need for case machining.
Built for riders who want real, usable power, this kit delivers a major increase in displacement using high-quality cylinders and forged pistons engineered for strength, reliability, and consistent performance.
Key Features:
- Converts M8 114” / 117” engines to 128 cubic inches
- Bolt-on design – no case boring required
- Precision piston & cylinder kit for 4.5” stroke engines
- CP-Carrillo forged pistons for durability and performance
- Multiple compression ratio options available (varies by setup)
- Compatible with a wide range of camshafts and supporting components
Performance Benefits:
Stepping up to 128” increases both bore size and overall displacement (typically around a 4.250” bore × 4.5” stroke setup), significantly improving airflow and power potential.
Expect:
- Stronger low-end torque and faster throttle response
- Increased horsepower across the entire RPM range
- Better acceleration and load-carrying performance
- A broader, more aggressive powerband
This is one of the most effective upgrades for riders looking to gain real-world power without jumping into full engine machining.
Build Recommendations:
To get the most out of your 128” setup, pair it with:
- Performance cam matched to your riding style
- Proper fueling upgrades (injectors / throttle body)
- High-flow intake and exhaust system
- Professional dyno tuning
Big bore builds rely heavily on airflow and tuning—matching the right components is key to maximizing both performance and reliability.
Bottom Line:
The Fuel Moto 128” Big Bore Kit is a proven, bolt-on displacement upgrade for Milwaukee-Eight 114 and 117 engines—perfect for building a strong street bike or a high-torque performance setup without the complexity of full engine machining.
