New engine for 2019 BMW R1250 GS and R1250 RT

IT’S NOT been the best-kept secret perhaps, but this is the 2019 BMW R1250 GS and RT, being launched this week.

And at the heart of the changes is an all-new Boxer engine, with variable valve timing, increased capacity, and a 136bhp peak power output, up 11bhp from the current bike. It’s now 1,254cc rather than 1,170cc, with a 1.5mm larger bore and 3mm added to the stroke (now 102.5x76mm up from 101x73mm). There are loads of other detail mods, including oil jet cooling for the piston undersides, new injectors, and a new unit gearbox design with updated wet slipper clutch.

But it’s the new variable-valve heads which are the big story. BMW’s used an all-new system dubbed ShiftCam, which uses a similar setup to that in most bike gearboxes. A slotted drum on the end of the camshaft is moved axially by an electronic actuator. The camshaft then slides along its bearings, moving from one set of cam profiles to another. One is optimised for low-speed engine running, with smaller lift and shorter duration, while the high-speed cam profile has more valve lift and duration, for the best breathing at peak engine speeds. As a result, the motor works better across the rev range, giving a wider spread of torque, cleaner and smoother running at idle, and can even use a lower idle speed.

Fuel consumption is also reduced, down a claimed four per cent from that change alone. The camchain now uses a quieter Hyvo toothed chain rather than the old roller chain, and the cams are designed so that each valve opens at a slightly different time. That increases the ‘swirl’ of the intake charge, further enhancing efficiency and reducing emissions. It’s all good stuff, though we guess that space considerations mean they could only fit the variable valve gizmo on the intake side, rather than on intake and exhaust cams.

Away from the engine, there’s a host of new electronic aids – Hill Start and ASC stabillity control are now standard, while a new optional Riding Modes Pro system adds more Dynamic riding modes. The semi-active electronic suspension is also moved up a level, with a new ‘Next Generation’ system, featuring automatic load compensation available on the GS and RT. The GS also has an optional ‘Sports’ suspensionpackage, with increased springrates and longer struts for even more travel.

We’ll be aiming to ride the new GS as soon as possible… More as we get it on the 2019 BMW range.