Fuel Moto 124” Big Bore Kit – Milwaukee-Eight (M8 107)
Step up your Milwaukee-Eight 107 with the Fuel Moto 124” Big Bore Kit—a proven bolt-on displacement upgrade designed to deliver strong, usable torque and horsepower without the need for case machining.
This piston and cylinder kit increases displacement to 124 cubic inches using precision-fit cylinders and forged pistons, giving your engine a major boost in airflow and overall performance while maintaining reliability for street and touring use.
Key Features:
- Converts M8 107” engines to 124 cubic inches
- Bolt-on design – no case boring required
- Precision piston & cylinder kit for 4.5” stroke engines
- Forged pistons (CP-Carrillo design) for strength and durability
- Multiple compression ratio options available depending on build
- Compatible with a wide range of camshafts and supporting upgrades
Performance Benefits:
Moving from 107” to 124” is a substantial jump in displacement, typically achieved with a 4.250” bore × 4.5” stroke combination. This increase allows the engine to move more air and fuel, directly translating into real-world power gains.
Expect:
- Stronger low-end torque and improved throttle response
- Noticeable horsepower gains throughout the RPM range
- Better roll-on acceleration and load-carrying performance
- A broader, more aggressive powerband
Real-world builds with 124” setups commonly show major gains in both horsepower and torque when paired with the right components.
Build Recommendations:
To maximize performance and reliability, pair your 124” build with:
- Performance camshaft matched to your riding style
- Proper fueling upgrades (injectors / throttle body)
- High-flow intake and exhaust system
- Professional dyno tuning
Displacement alone makes power—but airflow and tuning determine how much of it you actually use.
Bottom Line:
The Fuel Moto 124” Big Bore Kit is one of the most effective upgrades for Milwaukee-Eight 107 engines—delivering a significant jump in torque and horsepower with a straightforward bolt-on installation.
