Photos by Kevin Wing.

With its competition hard on the gas and more stringent Euro 5 emissions, noise and durability regulations looming on the 2020 horizon, for the 2019 model year BMW revamped all five of its boxer motorcycle models powered by the liquid-cooled flat-opposed twin. Bumped from 1,170cc to 1,254cc with a larger bore and longer stroke, the DOHC, 4-valve-per-cylinder boxers also received a form of variable valve timing (VVT) that increases power, broadens the powerband, improves fuel economy and lowers emissions and the required fuel AKI from 89 to 87.

Though all five liquid-cooled boxers were revamped for 2019, the R 1250 R and R 1250 RS have only recently arrived as 2020 models.

Cost and limited space on motorcycles make VVT more common in the automotive world, and to date it?s only been used in a few Japanese and Italian motorcycle models to open additional intake valves or increase intake valve lift and duration at higher engine speeds. BMW?s Shift Cam VVT is unique in that it slides or ?shifts? the boxer engine?s intake cams left or right, engaging either a partial or full-load cam lobe under certain loads at low speeds, or at 5,000 rpm regardless. The shift happens in milliseconds so it?s undetectable, but the result is a noticeable improvement in smooth grunt at low rpm and more power on top. The last Shift Cam R 1250 we tested in 2019 ? which has an identical engine to the R 1250 R reviewed here ? made 121.5 horsepower at 7,800 rpm and 92.5 lb-...