A video leaked online reveals crucial details about BMW’s upcoming R1250GS, the successor to its world conquering R1200GS. As well as showing the bike itself, the video goes into detail about the new cam system in the cylinder heads.
The “Shiftcam” system, according to the video, responds to the position of the throttle. An actuator and shift gate moves the intake cam sideways and engages a different profile. Lower amounts of right-wrist action will use the less aggressive profile with reduced lift, where as giving it the beans will shift to a more aggressive cam with more lift, unlocking more power. The video claims 143NM of torque (105.5 lb-ft) and 136 HP – that’s an 8% and 14% hike in power and torque respectively over the outgoing R1200GS.
This is different to Ducati’s Ducati Variable Timing (DVT) system seen on the Multistrada 1260 and Diavel. DVT advances and retards cam timing to alter valve overlap (with the cam profile remaining the same), resulting in a similar effect – higher torque at the lower end of the rev range with the same power at towards the top. It’s clever stuff.
The BMW Shiftcam system is more similar to Honda’s rather “marmite” VTEC technology where oil pressure activates and deactivates a cam, which in turn activates and deactivates sets of valves – effectively switching the engine between 4V and 8V on the intake sides. The big question will be whether the change in cam profile is smooth or rather abrupt, as Honda’s system was widely slated for.
More as we have it… For now, here’s the leaked video: