Water-cooled BMW R1250GS spied

SPY pictures of BMW's water-cooled 2013 R1250GS have been flying around forums over the Christmas break, giving us a chance to analyse some of the finer details of the bike that spells the beginning of the end for BMW's traditional air-cooled boxer twins.

Despite the 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 of the cooling duties are being done by water that runs around the engine – particularly the cylinder heads – and then back to radiators tucked up behind the side panels above each cylinder.

The new motor (and while it's still a boxer twin, it really is 'new' with no carry-over parts from the old engine) appears to be carried higher in the chassis than the old air-cooled unit, with the exhausts now exiting from the bottom of the cylinder heads rather than the front. The high cylinders mimic the firm's 20-year-old water-cooled boxer prototype, the R1 sports bike, which also carried its crank and cylinders high in an effort to increase ground clearance in corners.

Despite the new water-cooled engine and 1200cc-plus capacity, don't expect Multistrada-style performance from the new GS. It's never been BMW's aim to make its dual-sport the fastest on the market; instead it always relies on being the 'best' from an all-round ownership point of view; a strategy that clearly works, as it's been the firm's top selling model (and often the best-selling bike in Europe) for years on end. We're guessing that the new motor will offer something in the region of 120-130bhp, backed up with a torque curve resembling Ayers Rock.

The chassis is pretty much what we'd expect from a BMW GS; straightforward steel tubes with a Telelever front and and Paralever rear suspension. However, you can be pretty certain the new GS will feature the next-generation of BMW's ESA electronic suspension adjustment.

The styling ticks all the GS boxes: lopsided headlight (now with LED running lights), massive fuel tank, unusual lumps and bumps abound at the front while the back is bare apart from mounting brackets for the inevitable alloy-look panniers.

The new engine is matched with a new transmission, placing the shaft drive on the opposite side compared to the existing GS, a move that's led to the end can being repositioned to the bike's right hand side. As usual, we're expecting the base GS to be backed up with a more off-road style 'Adventure' version with wire wheels and other styling alterations.

Beyond the GS, the importance of this bike is that it will also form the basis of the rest of BMW's boxer range in the future. The new water cooled engine is sure to lead to a new R1250R and R1250RT over the next couple of years once the R1250GS is established – leaving no air-cooled models in BMW's range for the first time in the firm's history.

Images via: forums.pelicanparts.com