The wait is over. Harley-Davidson has debuted its new Milwaukee Eight engine, the newest powerplant for their Big Twin lineup.
First, some numbers: As predicted, there’s a 1750 cc (107 ci) and 1860 cc (114 ci) version of this engine. The standard motor will have oil-cooled heads, but there will also be a version with liquid-cooled heads. As was also predicted, there will be a single cam and two spark plugs per cylinder, and four valves (hence the name Milwaukee Eight). Those valves are said to offer 50 per cent better air flow, which also means there’s a new 55 mm throttle body.
Better airflow also resulted in better fuel efficiency, Harley-Davidson says (we haven’t heard how much better), but also allows for more power — the touring lineup supposedly has 10 per cent more torque available now, which would theoretically place them in the 156 Nm range. We haven’t seen horsepower figures for the new motors yet.
Some more numbers: Bore and stroke are 100 mm and 111.13 mm respectively for the oil-cooled 1750 cc (107 ci) motor. The liquid-cooled 1860 cc motor has a 102 mm bore and 114.3 mm stroke. We haven’t seen numbers for the other variations of the motor.
While the engine is still rubber-mounted, a single counterbalancer removes 75 per cent of vibration at primary idle, Harley-Davidson says; supposedly, prototypes actually featured 100 per cent vibration control, but lacked the feedback MoCo customers wanted. Engineers lowered idle speed to 850 rpm, but managed to improve charging system to 24 amps at idle (up 50 per cent) and 30 amps at 1,050 rpm.
Despite gossip the new engine wouldn’t have self-adjusting hydraulic valves, that isn’t the case. The Milwaukee Eight continues to use self-adjusting valves, and Harley-Davidson says they will not need adjustment over the lifespan of the motor.
Harley-Davidson also re-designed the exhaust routing, so riders aren’t cooking the inside of their legs in stop-and-go traffic.
The new oil-cooled 1750 cc motor will initially be available in Harley-Davidson’s touring lineup, as predicted (Street Glide, Road Glide, Electra Glide, Road King, Tri Glide). The liquid-cooled 1750 cc motor will power the Ultra lineup (Ultra Limited, Ultra Limited Low, Road Glide Ultra, Tri Glide Ultra) and the liquid-cooled 1860 cc motor will power the CVO lineup (CVO Street Glide, CVO Limited).
Check out all the pics that go with this story!