While the author reserves his comments on the trend for retro motorcycles – some of these are really well done, others should be taken out back and shot – BMW Motorrad has come up with its biggest boxer yet, the mill powering the Concept R 18 and Concept R 18/2. Displacing 1,802 cc, effectively some 901 cc per jug from the over-square 107.1 mm bore and 100 mm stroke, the “Big Boxer”, as BMW Motorrad calls it, is a torque monster as can be guessed from the specifications.
Producing 91 hp at 4,750 rpm, the issue here is not one of power but torque, and stump pulling handfuls of it. The Bog Boxer produces 158 Nm at 3,000 rpm with 150 Nm available to the rider’s right hand from 2,000 to 4,000 rpm, making the torque curve flat as a pool table.
It is obvious the market the boys from Munich is chasing is the “cruiser” and “power cruiser” segment. When Harley-Davidson used to dominate this niche, it’s market has been falling fast the past few years and this demographic has seen stiff competition from Indian Motorcycles, along with the newly released Triumph Rocket III and, having a following in its own right, the Ducati Diavel and XDiavel.
The Big boxer is not to be rushed and point-and-shoot sports riders should look elsewhere. The opposed-twin engine weighs a hefty 110.8 kg complete with gearbox and intake and redlines at 5,750 rpm, idling at 950 rpm.
For riders used to 13,000 redlines (like the author) this indicates the engine should, perhaps, be ridden at a rather more relaxed pace, using the engine torque to gently waft along the highway. Or, during the author’s Harley-Davidson period, taken on a footboard scraping, rear wheel chattering, pillion hanging on for dear life and screaming loud enough to be heard inside the helmet ride to Sungai Koyan.
Technology does dominate the Big Boxer, BMW Motorrad has made sure of that. There is a limit to how far you can push this retro nonsense, after all, despite the amount of money you could make pushing 70’s engine design to soy latte sipping, drainpipe jeans wearing hipsters.
What is retro is the air/oil-cooled engine which, to support the enormous pistons, comes with two outboard main bearings like the normal R-series twin but with an additional main bearing in the centre to carry the load. The quench and tempered steel crankshaft holds connecting rods and aluminium pistons with Nicasil coated bores.
‘Modern’ sensibilities include four-valves per cylinder in overhead configuration and twin-spark plugs. The camshafts are located above the crankshaft and driven by via a sleeve-type chain which BMW says shortens the pushrods and decreases flex and moving mass.
Unfortunately, despite the size and bulk of the Big Boxer, valve adjustments are done manually, no hydraulic valve lash adjustment here, thank you very much. The benefit of having the cylinders sticking out on either side of the bike, though, is valve adjustments are easily done with screw adjusters.
Completing the Big Boxer package is a six-speed transmission – gearbox sounds crude for a engine like this – with four shafts holding helical gears. Available as an option is reverse gear, driven by an intermediate gear and an electric motor which will, naturally add a few more kilos to engine weight but once you’ve crossed the 100 kg barrier, what’s a few kilos between friends.
Besides the Concept R 18 and R18/2, BMW Motorrad has not revealed where the engine might sit in the current model line up but we think a series of big power cruisers will be in the offing. This make sense, considering the current R NineT Heritage series of retro styled motorcycles has seen keen interest from riders wanting something different from the current crop of retro sports bikes.