BMW’S low tech whopper

New 1802cc twin has a separate gearbox, pushrods and locknut valve adjustment

BMW’S vast new boxer twin is an intriguing blend of new technology and old ideas. New details released by BMW show it combines all the latest tech you’d expect of a 2020 engine – four valve heads, fuel injection, sensors everywhere – with some ideas BMW came up with in 1936.

Whereas previous retros by Triumph, Kawasaki et al have been styling exercises applied to modern motors, the R18 engine takes retro to a far deeper level. The valves, for example, are actuated by pushrods running from two camshafts (one per cylinder) sitting at the top of the motor. It’s an arrangement first used by BMW in their 1936 R5. Though BMW imply pushrods are purely a nod to the past, there are practical benefits too: overhead cams would have made the already massive cylinders even taller and the bike would have been absurdly wide. And, at the low revs a cruiser operates, pushrod engines are pretty efficient – BMW claim 91bhp at 4750rpm, 116 lb.ft at 3000rpm and the motor passes Euro5 emission regulations.

Another low tech solution includes using a screw and locknut system instead of shims or hydraulics to adjust the valve clearances. The advantage of this is it’s a doddle to do, while the disadvantage is you end up doing it a lot. There’s no word on valve adjustment intervals. The gearbox is in a separate housing, as per the old days – so you’ll have to change the gearbox oil separately to the engine oil. Also, the shaft drive and universal joint exiting the gearbox are exposed, just like on BMW’S post-war classics. Bringing the R18 rather more up to date, owners can specify a reverse gear. This could come in handy – the engine alone weighs 110kg, so the whole bike could push 300kg.