Harley-Davidson introduced its all-new Milwaukee-Eight engine lineup in 2016, continuing its tradition of powerful V-twin engines. Instantly recognizable as a Big Twin, this engine debuted with two displacement options: 107 ci and 114 ci. Early models included four versions: an air-cooled 107, Twin-Cooled 107, Twin-Cooled 114, and Twin-Cooled 117. The 117 was exclusive to select touring bikes, Ultra models, and CVO models.
The M-8 107 cranks out about 10% more torque than its Twin-Cam predecessor, delivering 111 lb-ft and 87 horsepower, giving riders strong pull-through across the range. The M-8 114 steps it up to 124 lb-ft and 100 horsepower, while the Twin-Cooled 117 cubic-inch engine delivers 130 lb-ft of torque and 105 horsepower.
Harley’s Screamin’ Eagle performance division offers plenty of upgrades for those looking to push their engine further. For top-tier performance, the M-8 VVT (Variable Valve Timing) 121 found in CVO models is a standout. VVT enhances low-end torque without compromising top-end power, making this engine a must-consider for serious performance enthusiasts.
Performance Specifications:
- Milwaukee-Eight 107: 1,745 cc, 108–112 lb-ft of torque, 87 horsepower*
- Milwaukee-Eight 114: 1,868 cc, 119–124 lb-ft of torque, 94–100 horsepower*
- Milwaukee-Eight 117: 1,923 cc, 124–130 lb-ft of torque, 94–105 horsepower*
- Milwaukee-Eight 121: 1,977 cc, 145 lb-ft of torque, 127 horsepower*
* Torque and horsepower may vary depending on model and engine tuning.
More power often means more heat, but Harley-Davidson has solutions in place. A larger oil reserve aids cooling, while the cooling fins on the engine remain functional. The Twin-Cooled engines feature liquid cooling around the exhaust valves, helping to prevent heat damage and performance loss. Additionally, the cylinder deactivation system shuts off the rear cylinder at idle to further manage heat.
Maximizing Efficiency and Power
Harley-Davidson also slimmed down the primary drive for a narrower profile, making it more comfortable for shorter riders. An anti-backlash gear and wide primary drive chain smooth out the engine’s power pulses, while a slipper clutch connects to a six-speed transmission. The belt drive and refined drivetrain ensure a quieter ride than previous engines.
A counterbalancer helps reduce vibrations typical of a 45-degree V-twin, with rubber mounts providing additional isolation for the rider and passenger. Some purists argue this dampening removes the engine’s “feel,” but it certainly enhances comfort.
Harley has also addressed vibration complaints, offering a full suite of ride-safety electronics on many M-8 powered models. Enhanced infotainment systems and larger TFT screens are now common, backed by a 50% boost in charging system output—perfect for those who enjoy adding extra gadgets.