The BMW R 1250 GS and R 1250 RT unveiled in September 2018 introduced ShiftCam to series-production BMW motorcycle engines. Boxer displacement grew from 1,170 to 1,254 cc, accompanied by variable intake-valve timing and lift.
Each intake valve has two different cam profiles, one for partial load and one for full load. The camshaft moves along its axis to select the profile operating the valve. An electric actuator and a shifting gate produce this movement; selection depends on engine speed and load.
Under partial load, the intake valves open less. The two intake valves in each cylinder also open at different times and with different amounts of lift, increasing swirl in the incoming mixture. The full-load profile provides maximum intake-valve lift.
The design aims to combine smooth, economical running at partial load with effective cylinder filling when more power is required. On the R 1250, electronic control therefore selects a mechanical valve-motion profile as well. That interaction between control and moving hardware is the key to understanding ShiftCam.