Milwaukee-Eight Sensations

We were invited by Harley-Davidson to Tacoma, USA, to ride their 2017 touring range with the new Milwaukee-Eight engines. Here is an account.

- Aspi Bhathena

THERE ARE ACTUALLY three versions of the Milwaukee-Eight, named after the V-twin’s doubled number of valves. The basic Milwaukee-Eight 107 gets its larger 107-cubic inch (or 1,745 cubic centimetres) capacity from a larger bore (100 millimetres, up from 98.3 mm) and an unchanged 111.1-mm stroke, gaining a new oil-cooling system around its cylinder-heads at the same time. The Ultra Classic uses a liquid-cooled version, featuring small radiators in the fairing lowers, as it did with the Twin Cam 103 unit. The exotic CVO models are powered by a larger Milwaukee-Eight 114 engine whose dimensions of 102 x 114.3 mm stretch the capacity to 1,868 cc.

Harley’s traditional 45-degree cylinder angle and pushrod valve operation remain, but the 107 has a new, more angular air-filter cover. Internal changes include a move from twin to single camshaft, made possible by the smaller valves’ reduced spring pressure. As in Project Rushmore, the engine changes were made in response to the feedback received from existing H-D riders who demanded not only more power and cooler running, but reduced vibration and width.

The Milwaukee-Eight design delivered all that, with the four-valve layout’s improved flow being most responsible for the extra performance (just as the Japanese manufacturers said about their 16-valve fours in the early 1980's). There is roughly 10 per cent more torque for a good chunk of the rev-range, according to H-D, with a peak torque figure of 151 Nm at 3,250 revolutions per minute against the Twin Cam unit’s 138 Nm. The reduced vibration comes from a new balancer shaft, located low down at the front and carefully designed to achieve the right compromise between increased comfort and retained character.