The New Harley-Davidson Milwaukee-Eight Engine Debuts

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What you are looking at above is Harley-Davidson’s ninth iteration of its “Big Twin” engines. It’s called the Milwaukee-Eight, named after Harley-Davidson’s home town and the fact that the engine head design employs a very modern eight valves in total (four per cylinder head).

Time will tell if the Milwaukee-Eight becomes as iconic as Harley-Davidson’s other designs, like the Flathead, Knucklehead, Panhead, etc. But, we do know that the Milwaukee-Eight marks a more modern approach to engine design from the Bar & Shield brand.

To this end, Harley-Davidson says that the new power plant offers a quicker throttle response, more passing power, purer sound (whatever that means), and a smoother ride (read: less vibrations).

The Milwaukee-Eight will first be used on Harley-Davidson’s touring and trike lines, though we can expect the engine design to permeate through Harley-Davidson’s lineup.

“The Milwaukee-Eight engine carries the legacy of Harley-Davidson Big Twins into the future,” said Chief Powertrain Engineer Alex Bozmoski.

“While respecting the essential Big Twin character, we’ve created an all-new motor. Every aspect of performance, durability and styling has been improved as a direct response to the voice of Harley-Davidson customers around the world.”

For now, the Milwaukee-Eight 45° v-twin engines will be offered in two displacements and three variations:

  • Milwaukee-Eight 107 (107ci, 1750cc) – precision oil-cooled cylinder heads for the Street Glide/Street Glide Special, Road Glide/Road Glide Special, Electra Glide, Ultra Classic, Road King, and Freewheeler models.
  • Twin-Cooled Milwaukee-Eight 107 (107ci, 1750cc) – liquid-cooled cylinder heads for the Ultra Limited/Ultra Limited Low, Road Glide, Ultra, and Tri Glide Ultra models.
  • Twin-Cooled Milwaukee-Eight 114 (114ci,1870cc) – liquid-cooled cylinder heads for the CVO Limited and CVO Street Glide models.

As one would expect, the Milwaukee-Eight engine produces more power than its predecessor, 10% to be precise. The power increase comes in part from the added increase in displacement, but Harley-Davidson has also upped the compression ratio.

Additionally, the eight-valve head design has an increased 50% intake and exhaust flow capacity, while dual-spark plugs ignite the combustion.

Harley-Davidson also touts the Milwaukee-Eight engine’s ability to increase acceleration (11% quicker on the 107ci engine, and 8% on the 114ci engine), due mostly to the fact that the Milwaukee-Eight engine weighs the same as the Twin Cam motors it replaces, while obviously having a power advantage.

Heat management has been improved as well (due to refined precision cooling techniques), while engine vibrations have also been reduced by a single internal counter balancer that cancels 75 percent of primary vibration at idle.

We will see the Milwaukee-Eight engine on the 2017 Harley-Davidson touring and trike models, though we can expect the Milwaukee-Eight architecture to be used on other forth-coming models in Harley-Davidson’s arsenal. We expect that process to be gradual, and over the next few years.

Source: Harley-Davidson

Jensen Beeler

Despite his best efforts, Jensen is called one of the most influential bloggers in the motorcycle industry, and sometimes consults for motorcycle companies, whether they've solicited his expertise or not.