Harley-Davidson Revolution Max 1250 Engine: 21 Essential Fast Facts

Now that everyone has settled down after the debut of the 2021 Harley-Davidson Pan America 1250 and Pan America 1250 Special, let’s take a closer look at the absolutely all-new Revolution Max 1250 engine that powers the two new ADV bikes from The Motor Company. Don’t worry—we are keeping it simple. Plus, we have plenty of cutaway photos to sate your curiosity.

  1. The Revolution Max 1250 is a 60-degree V-twin. That’s the same angle as the V-Rod’s Revolution motor, which Harley-Davidson produced from 2001 to 2017. You might recall that Porsche was in on the development of that Revolution motor. The current Revolution X motor used in the Street 750 also uses a V with a 60-degree angle.

Harley-Davidson Revolution Max: New Motor

  1. It is a short-stroke motor. The bore is 105mm and the stroke just 72mm. Displacement is 1247cc.
  1. The redline comes at 9500 rpm. On the way there, it produces peaks of 150 horsepower and 94 ft-lbs of torque.

Harley-Davidson Revolution Max: All New Powerplant

  1. The 60-degree V-twin leaves room for dual downdraft throttle bodies. The 45-degree Milwaukee-Eight V-twin uses a single throttle body. The throttle bodies’ fuel delivery is optimized for each cylinder.
  1. The 11-liter airbox houses tuned velocity stacks. The air filter is washable.

Harley-Davidson Revolution Max: Liquid-cooled 60-Degree V-Twin

  1. Like other 60-degree V-twin Harley-Davidson motors, the Revolution Max 1250 is liquid-cooled. This allows for tighter tolerances inside the motor, which increases performance and decreases emissions. The engine oil is also liquid-cooled to further keep the motor temperature under control. Additionally, the motor is a dry-sump design.
  1. The low-pressure oiling system is a triple pump design. Excess oil is pumped out of the crankcase, stator cavity, and clutch cavity to reduce drag. Oil is sent via the center of the crankshaft to the main bearings and connecting rod bearings. That requires less than 70 psi, which allows the motor to spin more freely.

Harley-Davidson Revolution Max: DOHC

  1. With a 30-degree offset for the connecting rods, the Revolution Max 1250 motor has a 90-degree firing order. According to Harley-Davidson, this smooths out the motor at high rpm and provides superior off-road performance at lower engine speeds.
  1. The top end is a DOHC design, and there are four valves per cylinder. There are also two spark plugs per cylinder for complete combustion.

Harley-Davidson Revolution Max: Pan America ADV Motorcycle

  1. All four cams have variable valve timing, with each cylinder getting different settings for a wider powerband. The variability works over a range of 40 degrees of crankshaft rotation. The change in the cam timing is performed by a solenoid plunger operating on ported hydraulics.
  1. The valves on the Revolution Max 1250 use hydraulic lash adjusters. It is a self-adjusting, no-maintenance design. The valves and finger followers are in constant contact and adjust as needed when engine temperature changes. Inside, the exhaust valves are sodium-filled to help dissipate height.

  1. Magnesium is used for the rocker covers, cam covers, and primary cover. This is a weight-saving strategy.
  1. The cylinder heads are cast aluminum. The frame attaches to the head, so the mounting point is flexible while the combustion chamber is rigid. Targeted heat treating is employed to facilitate the dual duty.

  1. The cylinders are single-piece aluminum, with the bore getting a nickel silicon carbide (CODIAC) coating.
  1. The high-compression 13:1 pistons are forged aluminum. The piston skirt gets a low friction coating, and the base is chamfered to ease maintenance. The piston rings are low-tension and do not quire a compression tool during installation.

  1. There are two balancers to smooth out the motor. The primary balancer is a chain-driven design inside the crankcase. Its job is to smooth out the vibration created by the connecting rods, crankpins, and pistons. It also lessens side-to-side imbalance than can come with offset cylinders. A second balancer sits between the cams and ahead of the cylinder head to reduce whatever vibrations get past the primary balancer.
  1. The motor is a stressed member, so it acts as part of the chassis. The front-, mid-, and rear-frame pieces all bolt directly to the engine. The result is a highly rigid chassis.
  1. The Harley-Davidson Revolution Max 1250 has a six-speed transmission. Roller bearings support the shift drum, while the shift-shaft support bushings are coated with Teflon.

  1. The clutch is cable-actuated, and has both slipper and assist functions. The clutch basket uses eight friction plates.
  1. Although 91 octane fuel is recommended, the 1250 will run on lower octane when needed, thanks to the ECU.
  1. Here is what said Harley-Davidson Chief Engineer Alex Bozmosk has to say about the new powerplant: “Through its history, Harley-Davidson has embraced technological evolution while respecting the heritage of our brand, with engines that produce real-world performance for real-life riders. The Revolution Max 1250 is a clean-sheet, advanced-design effort that will carry Pan America riders over new horizons with reliability, efficiency, and exciting performance.”