A new Harley-Davidson engine is a big deal, particularly when it falls into the ‘Big Twin’ category. And as such, 2017 promises to be a landmark year for the brand.

Because following on from a heritage that spans only seven generations of engine since 1914, Harley is set to launch a new ‘Big Twin’ – the Milwaukee-Eight. That name is intended to go down in history alongside its forebears, sitting alongside predecessors like the Flathead, Knucklehead, Panhead, Shovelhead, Evolution and Twin Cam.

Coming in at a hefty 107ci (that’s 1753cc, or thereabouts), the Milwaukee-Eight is, like so many of its predecessors, titled in recognition of its cylinder head design. More specifically, the ‘Eight’ refers to the number of valves – four of them for each cylinder.

You might well be asking what’s so special about a four-valve-per-cylinder engine. Harley’s made them before in the V-Rod and the new Street 500 and 750, so why the fuss? Because the new engine is a classic Big Twin, which means it’s air-cooled and those valves are actuated via pushrods to ensure it keeps the classic H-D look while coming up to date in terms of valve count.

Pushrod, four-valve engines are few and far between, but as capacities grow and emissions regulations get tighter, the demand for the improved gas-flow and better burn offered by four-valve heads gets stronger.

We’ve known a new engine carrying the Milwaukee-Eight name has been coming for a long time. Harley applied for trademarks on the name back in 2014, but no details have emerged until now. Recently, two close-cropped pictures emerged online showing key elements of the engine – its cylinder head and the airbox bearinging the “107 Milwaukee-Eight” legend.

Milwaukee Eight 1

It appears the new engine ups the camshaft count from two in the current big Harley twins to three or even four, all still mounted down near the crankshaft, not up in the cylinder heads.

The result, particularly when allied to a 107ci capacity, should amount to a useful jump in power and torque while, importantly, cleaning up emissions for years to come.

The engine is also designed with 107ci as a starting point, with plenty of scope for enlargement in the future. There’s already talk that CVO models will get a bigger, 117ci version.

Initially expect to see the engine in just a couple of models in Harley’s ‘Touring’ range in 2017. Over time, the design will spread to more machines.

Milwaukee Eight 2