Harley-Davidson Launches 107” & 114” Milwaukee-Eight Engines

The 2017 Milwaukee-Eight V-Twin will be offered in a 107″ version for Harley Tourers and Trikes and a 114″ variation for its premium CVO models. (Photos by Brian J. Nelson, and Harley-Davidson)

Stop the press! The rumors are true. Harley-Davidson has indeed developed a new engine called the Milwaukee-Eight. The eight valve V-Twin comes in both a 107” version for Harley-Davidson Touring motorcycles and Trikes and a 114” variation for The Motor Company’s top-shelf CVO line. The new valvetrain design comes with an impressive list of proposed improvements – more power, better efficiency, lower idle, less heat, and less noise.

American Iron brass Buzz Kanter and Steve Lita got a chance to speak with Harley’s Product Planning Director Paul James and Chief Engineer, New Products Alex (Boz) Bozmoski about the Milwaukee-Eight for an exclusive American Iron Magazine first look article in Issue #341 that hits newsstands Sept. 13. Additionally, American Iron Editor Lita has already gotten a chance to sample 2017 Harleys with both the 107” and 114” versions of the Milwaukee-Eight, and his first ride review will run in American Iron Magazine Issue #342. Click here for some of editor Steve’s first ride impressions.

More power, better efficiency, lower idle, less heat, and less noise – what’s not to like about Harley’s new Milwaukee-Eight 107! Find out how many of these claims are true in American Iron Magazine Editor Steve Lita’s first ride review in Issue #342.

Until then, here’s a few of the Milwaukee-Eight’s key features gleaned from the American Iron Magazine article along with the engines’ specs. If you’d like to hear the new Milwaukee-Eight, be sure to check out American Iron’s YouTube channel.

• Because these are touring machines, design emphasis was placed on rider and passenger comfort (vibration), heat control (from engine and exhaust), and functionality (improved electrics and electronics). From what we were told, Harley met these goals.

• While the engine weighs just about the same as the Twin Cam it is replacing in 2017—at least on the touring and trike models—we were told the Milwaukee-Eight is a clean sheet design, going back to a single cam configuration, with pushrod-actuated four valves per head, hydraulic lifters, and dual sparkplugs per head.

The Milwaukee-Eight 107″ heads look different for good reason. In addition to increasing from two to four valves per cylinder, the heads have been treated for advanced combustion design and flow work, said to generate almost a 50% increase in flow.

BJN37718

Visible in blue is the precision oil cooling passage.

The Milwaukee-Eight 107 heads look different for good reason. In addition to increasing from two to four valves per cylinder, the heads have been treated for advanced combustion design and flow work, said to generate almost a 50% increase in flow.

Pushrod-activated rocker arms control the two intake and two exhaust valves per head. Once set, valve adjustments are done for life.

 

 

 

 

 

 

 

 

 

 

• Harley said there are two versions in relation to engine cooling as well, as bikes without lowers will feature Precision Oil-Cooled engines, while bikes with lowers will employ the Precision Water Cooling system, with the radiators housed in the lowers a la RUSHMORE style. Before you get any bright ideas about retro-fitting a Milwaukee-Eight into an older bike, be aware that the engine mounting points have changed.

• The flywheel weight is the same as on the Twin Cam, but Harley has achieved 20% more rotational inertia with this engine. This aids in smoothing the driveline and producing a broad torque curve that pulls all the time. Redline is 5,500 rpm, slightly higher than a Twin Cam. A single internal engine counter-balancer is tuned at 75%, and the engine is rubber-mounted for less overall vibration to the rider and passenger.

• The heads have been treated to advanced combustion design and flow work, generating almost a 50% increase in flow. The intake and exhaust valve diameters are 40mm and 32mm respectively. Add the dual sparkplug (two per cylinder) design for a more complete burn, and you can see that this is not just a warmed-over Twin Cam design. There’s a new four-post-coil ignition with torque-based ECM with active knock sensors. There is independent control of the front and rear cylinder firing, with the front two coil outputs firing together and rear two firing together. Sequential Port Fuel injection is retained with a single throat inlet throttle body made of plastic. A bump up in compression ratio to 10:1 (107″) or 10.5:1 (114″) from the Twin Cam’s 9.7:1 means premium-grade fuel will be required.

• The single camshaft is utilized for its lower friction qualities, and it is chain driven. Thanks to a hydraulic lifter to pushrod connection from cam to rocker arm, you will never have to adjust the valvetrain from left to right, as they are now factory-set for life!

• It’s larger, more powerful, offers quicker acceleration, and produces 10% more torque. It should prove to be two to three bike lengths faster from 0-60 mph and one to two bike lengths faster from 60-80 mph in top gear.

The more powerful Milwaukee-Eight 107″ should make Harley’s tourers “two to three bike lengths faster from 0-60 mph and one to two bike lengths faster from 60-80 mph in top gear.”

2017 Milwaukee-Eight Engine Specs:
Engine:                 107″                  114″            TC 103 rubber mount
Cylinder angle:    45 degree      45 degree              45 degree
Bore:                      3.937″               4.01″                      3.875″
Stroke:                  4.375″               4.5″                        4.374″
Compression:    10:1                  10.5:1                       9.7:1
Valvetrain:      Four valves per cylinder      Two valve per cylinder
Ignition:            Four plug four coil               Two plug one coil
Torque: 114 ft-lb. @ 3250 /  124 ft-lb. @ 3250 / 104.7 ft-lb. @ 3250
Starter:                 1.6 kw               1.6 kw                  1.2 kw
Charging system: 24-25 amps / 24-25 amps / 17 amps
Fuel system:      ESPFI             ESPFI                     ESPFI
Oil capacity: 4.5 quarts      /   4.5 quarts    /          4 quarts
Idle speed:      850 rpm      /     850 rpm    /          1050 rpm

The new Harley Milwaukee-Eight will power The Motor Company’s 2017 touring motorcycles and baggers.

Harley-Davidson’s Big Twins over the Years
F-Head (JD) 1914-1929
Flathead 1930-1948
Knucklehead 1936-1947
Panhead 1948-1965
Shovelhead 1966-1984
Evolution 1984-1998
Twin Cam 1999-present
Milwaukee-Eight 2017-

Our First Ride Impressions of Harley’s New Milwaukee-Eight

Cornering on the 2017 Milwaukee-Eight-equipped Road King felt more agile than ever.

Cornering on the 2017 Milwaukee-Eight-equipped Road King felt more agile than ever.

American Iron Magazine editor Steve Lita was fortunate enough to get in a day of riding on the new 2017 Harley-Davidson Touring models featuring both versions of the new Milwaukee-Eight engine; standard 107″ and CVO models equipped with the 114″ version.

The first thing you notice when you start up the new Milwaukee-Eight is, well, the precise and consistent starting. Thanks to a new automatic compression release and a more powerful starter motor, the engine comes to life every time without a hitch or a hiccup, which can’t be said for Twin Cam models. Once the engine settles to life at a calm 850 idle rpm, you’ll recognize the traditional Harley rumble, albeit a little smoother. Don’t get me wrong, this engine is not sewing machine-boring, it still has that chugging cadence to it.

The 107" Milwaukee-Eight, staying true to Harley's Big Twin tradition while leaping forward.

The 107″ Milwaukee-Eight, staying true to Harley’s Big Twin tradition while leaping forward.

Click the bike into first gear and release the clutch, and you’ll be pleased with the easier feeling on your left hand. Roll on the throttle easy, the Milwaukee-Eight smoothly pulls this heavyweight up to speed. But gun the throttle, and get ready for an aggressive bark from the stock exhaust. Thanks to less drivetrain noise and the added cubic-inches, the exhaust emanates an aggressive tone. After my first ride I commented to Harley engineers how much I liked the sound of the bike.

Unfortunately, I didn’t have access to a timed acceleration course, but suffice it to say the seat-of-the-pants-feeling under hard acceleration was that the new bikes pull away from a stop or roll on at speed harder than before. This Milwaukee-Eight pulls hard all the way to the 5500 redline, and I found the rev limiter many times when not judiciously watching the tach. I felt consistent thrust all the way up the tach range without the power petering off. It just pulls, pulls, pulls, and then smack! You’re on the limiter. Step up to the larger 114″ Milwaukee-Eight, which is available only in the CVO models, and get ready for a kick in the butt over the 107″ version; you will definitely feel the difference in power output.

And the 114" Milwaukee-Eight, a CVO-only option that will blow your socks off.

And the 114″ Milwaukee-Eight, a CVO-only option that will blow your socks off.

All of that is great for straight-line riding, but what happens when you throw the new Touring models into a curve? Much improvement has been made to this line of bikes, and the new 2017 models can handle some twisties better than ever before. New front fork updates feature SHOWA Dual Bending valve (SDBV) technology, which is similar to current cartridge fork inserts, but more adept for mass production use. Out back is a hand-adjustable SHOWA emulsion shock. Turn the adjustment knob 23 times to allow for 25mm of total adjustment. No more worrying about blowing out air shocks. Confidence in riding through corners at high speed is greatly increased.

The 114" CVO Touring Model handles better than you could imagine for a Big Twin.

The 114″ CVO Touring Model handles better than you could imagine for a Big Twin.

My overall riding impression of these new Milwaukee-Eight-powered models is that Harley has taken all the right feelings and emotions of the previous engine and refined them, doing so with new high-tech components. The looks of the engine are right. It’s not some foreign, radical departure. Yet under the skin, the internal components work in better harmony than before. I think of this engine as a well-sorted Big Twin. It’s better than you ever thought the Big Twin family could perform.

For the full first ride review of the all-new Milwaukee-Eight Touring models, pick up a copy of Issue #342. In Issue #341, on sale 9/13, we give you everything you need to know about the new engine platforms.