Often considered hidebound to tradition, Harley-Davidson isn’t known for radical or rapid change. But as Dylan crooned, the times they are a-changin’. In the past few years the Motor Company has introduced an all-new, liquid-cooled engine platform (the Revolution X found in the Street 500/750), added “precision” liquid cooling to several of its Touring models and created major buzz with its Project LiveWire prototype electric bike.
For 2017, Harley-Davidson will launch the ninth generation of its venerable Big Twin, called the Milwaukee-Eight in honor of its birthplace and its number of valves—twice as many as found on the Twin Cam motor that’s been in the lineup since 1999. Harley-Davidson says the new engine platform provides faster throttle response, more torque, better sound, improved fuel economy and a smoother ride.
Other changes for 2017 include all-new front and rear suspension for Touring models, available ABS and Smart Security System for the Street 500/750 models, updated CVO models (Limited, Street Glide and Pro Street Breakout) and a full selection of street-legal Screamin’ Eagle Performance components for the Milwaukee-Eight, including Stage I, II and III kits that deliver up to 24 percent more torque.
The Milwaukee-Eight, which retains the classic 45-degree V-twin architecture, will power all 2017 Touring and Trike models, in two displacements and three variations:
- Milwaukee-Eight 107 (107 cubic inches, 1,750cc) with precision oil-cooled cylinder heads for the Street Glide, Street Glide Special, Road Glide, Road Glide Special, Electric Glide Ultra Classic, Road King and Freewheeler models
- Twin-Cooled Milwaukee-Eight 107 with liquid-cooled cylinder heads for the Ultra Limited, Ultra Limited Low, Road Glide Ultra and Tri Glide Ultra models
- Twin-Cooled Milwaukee-Eight 114 (114 cubic inches, 1,870cc) with liquid-cooled cylinder heads for the CVO Limited and CVO Street Glide models
Compared to the Twin Cam 103 and 110, the Milwaukee-Eight’s increased displacement, higher compression ratio and four-valve cylinder heads, which provide 50 percent more intake and exhaust flow capacity, result in 10 percent more torque across the board. Bikes equipped with the new engine are claimed to accelerate much faster off the line (8-11 percent quicker at 0-60 mph) and in top gear roll-ons (11-12 percent quicker at 60-80 mph).
Better air flow and combustion, including the use of dual spark plugs for each cylinder, are said to improve fuel economy. Precision oil or liquid cooling of the cylinder heads as well as repositioning the rear exhaust pipe and relocating the catalytic converter improves heat management, providing a more enjoyable riding experience for the rider and passenger.
As with the Twin Cam engine, the Milwaukee-Eight’s rocker arm-actuated valves never need adjustment. But instead of the Twin Cam’s dual camshafts there’s a single, chain-driven camshaft that’s lighter, quieter, less complex and reduces friction. The rubber-mounted Milwaukee-Eight uses an internal counterbalancer to cancel 75 percent of primary vibration at idle, for a less eyeball-shaking experience at stops.
Harley says the new engine’s reduced mechanical noise allows the exhaust note to take on richer tone. Other improvements include a 50 percent increase in charging output for powering accessories, slimmer primary and air cleaner covers for more legroom, and—always important on Motor Company machines—enhanced curb appeal. And all bikes with the Milwaukee-Eight are equipped with a low-effort Assist and Slip Clutch.
We’ll get a chance test ride 2017 models equipped with the Milwaukee-Eight at Harley-Davidson’s press launch next week. Stay tuned for our riding impressions.