Spy pictures of BMW's water-cooled 2013 R1250GS would seem to spell the beginning of the end for BMW's traditional air-cooled boxer twins.
Despite cooling fins on the cylinders and the lack of obvious radiators, there's no doubt this is a water-cooled motor. While BMW is still using a certain amount of air cooling, the lion's share is being done by water that runs around the engine – particularly the cylinder heads – and back to radiators behind side panels above each cylinder.
The new motor, which shares no parts with the old engine, is carried higher in the chassis than the air-cooled unit, with exhausts exiting from the bottom of the cylinder heads rather than the front. It's reminiscent of BMW's 20-year-old water-cooled boxer prototype, the R1, which had a sinmilkar configuration.
Despite the new water-cooled engine and 1200cc-plus capacity, don't expect the performance to change much. BMW's aim for the GS has always been to be an all-round 'best' and it's been the firm's top selling model (and often the best-selling bike in Europe) for years. Expect about 120-130bhp from the new motor.
The chassis is pretty much standard GS; steel tubes with a Telelever front and and Paralever rear suspension, but look for the next-generation of BMW's ESA electronic suspension adjustment.
The styling will continue with a lopsided headlight (now with LED running lights), massive fuel tank, unusual lumps and bumps at the front while the back is bare apart from mounting brackets for panniers.
The new engine is matched with a new transmission, placing the shaft drive on the opposite side compared to the existing GS, so that the silencer has been repositioned to the bike's right hand side. Expect the usual 'Adventure' version with wire wheels and other styling alterations.
Beyond the GS, this bike will form the basis of the rest of BMW's boxer range in future. So look fo water cooled R1250R and R1250RT models in future and the end of the air-cooled boxers, that have defined the marque since the late 1920s.––Paul Duchene
