Here Are All the Juicy Bits of Harley-Davidson's Intoxicating Milwaukee-Eight VVT 121

The Milwaukee-Eight breed of engines has been around for just seven years, having been introduced in 2016 as a member of the historically relevant big twin bre. It first came with displacements of 107 and 114 ci, but later down the line, the 117 came to be, as did several crate variants that take displacement to as high as 131ci.

So the 121 used in the two new bikes is by no means the largest of its kind available, but it is so as far as engines fitted from the factory lines are concerned. Moreover, the powerplant will only be offered for the two CVOs Harley revealed this week, so it's special in its rarity as well.

First, the basics. Harley never made a secret of the tech it produces, so all the traits of the engine are in its name. We're talking about a piece of technology with a displacement of 121ci (1,977cc) in a 45-degree, V-Twin configuration.

Compared to the Milwaukee-Eight 117 engine usually fitted on Street and Road Glides, this one produces 9.5 percent more horsepower and eight percent more torque. In simple numbers, that's 115 hp at 4,500 rpm and 189 Nm of torque at 3,000 rpm. All of that power is handled through a six-speed Cruise Drive transmission.

The key technology in this unit is the Variable Valve Timing (VVT). This is used to advance and retard the camshaft timing in a range of 40 degrees of crankshaft rotation and 20 degrees of camshaft rotation. As a result of this, fuel consumption drops a bit. As per the bike maker's numbers, that would be anywhere between three and five percent compared to a standard drive cycle engine. It may not seem like much, but in the long haul it could make a difference in the rider's pockets.

Compared to the 117, the new engine also has an improved cooling system, achieved by means of tweaks performed to the exhaust valve on each cylinder head, new channels for coolant flow, and a thermostatically controlled fan that directs airflow below the bike. All of this should help improve thermal comfort for the rider, especially when the bike is not moving all that fast and air temperatures are high.

To help boost torque and also help with fuel consumption, Harley increased the compression ratio (now at 11:4:1, up from 10:2:1). Both torque and horsepower get a boost thanks to the higher lift and longer duration camshaft.

Because emission levels are of concern these days, Harley designed a new intake track to help bring levels down, while the throttle body diameter grew from 55 mm to 58 mm. This part is also fitted closer to the intake valves to help with airflow.

Air intake is handled through an aluminum manifold, with new induction bits increasing the mass flow by 7.5 percent compared to the 117, and port velocity by 10.3 percent. The cherry on the cake, Harley replaced the Heavy Breather seen on previous CVO Glides with a new airbox that takes air volume to 50 percent higher, at four liters. The company also promises that since the airbox is lighter and simpler in design than the Heavy Breather, the intake sound is significantly reduced.

Not the same can be said for the other end of the engine. There, a new exhaust system with a muffler diameter of 4.5 inches (up from four inches) is said to provide a tone and level that are "intoxicating,” especially when the rider is accelerating.

With all of the above tweaks, the Milwaukee-Eight VVT 121 forms the heart of the 2023 CVO Street Glide and Road Glide motorcycles. Both of them are for the time being just images and details on a screen, but Harley plans to show them in the flesh soon.

The first public appearance of the two motorcycles will take place over the weekend of July 13, when the bike maker kicks off the centenary celebrations in its hometown of Milwaukee, under the inaugural Homecoming Festival umbrella.

The same month, the two CVOs will go on sale, with prices set to start at a whopping $42,999. In standard form, each of the two models is offered in Dark Platinum with Bright Smoked Satin, but there is the extra option (also meaning extra money) of getting your hands on a Road or Street Glide in a combination of Whiskey Neat and Raven Metallic.

No matter the option chosen, the engine will always come in gloss black, with either chrome or orange accents.