In what is proving to be one of the longest and most drawn-out of teaser campaigns in motorcycle history, BMW has revealed more details of the forthcoming R18 cruiser engine, which will feature the largest-capacity boxer engine of all time.
BMW started teasing the bike back in 2016, using various concept bikes to pave the way for the all-new cruiser which will be called the R1800. Now the German firm has revealed more details about the engine which promises to be not just the biggest capacity but also one of the most powerful in the cruiser class, with over 90bhp.
This new ‘Big Boxer’ engine has played a key role not just in the two BMW prototypes – the Concept R18 and the Concept R18/2 – but also in the custom bikes backed by BMW, these were named ‘The Departed’ by custom-builders ZON and ‘Birdcage’ by Revival Cycles. These paved the way for the new production bike which stated in 2016 with the concept R5 Hommage bike.
The new cruiser is centred around that all-new engine which, although it’s completely new, has been designed and engineered with BMW’s long history of boxer-engine motorcycles in mind.
The R18 engine has a capacity of 1802cc which is hugely bigger than the current largest boxer engine of 1254cc and has clearly been styled to hark back to the earliest examples of the boxer engine layout.
The capacity comes from a huge bore size of 107.1mm in combination with a 100mm stroke, producing a peak power figure of 91hp at 4750rpm. Combined with the power figure is a thumping torque figure of 158Nm at just 3000rpm which is going to give the cruiser, even if it’s heavy, some serious low-down punch.
BMW is making a big deal of the torque with 150Nm available between 2000rpm and 4000rpm, which, in combination with the large flywheel mass BMW says creates a very smooth engine.
The new R18 motor may be the latest offering from BMW but it retains the old-school air/oil cooling but combines that with modern four-valve heads and OHV valve drive and twin-spark ignition.
BMW has made it clear the old R5/R51 models dating back to 1936 to 1941 and the R51/2 of 1950 were inspirations for the engineering with two camshafts driven by the crankshaft via a sleeve-type chain.
One traditional engineering element is the use of valve clearances being adjusted using the classic screw and locknut for each valve rather than the more commonly used hydraulic systems used on modern engines.
What can we expect to see on the production bike?
The key concern during the development of this bike is how the German company could ensure it is seen as ‘authentic’ and sits with the cruiser class that is dominated by American bikes from Harley-Davidson and, more recently, Indian.
A firm design clue to the direction BMW is aiming for with the design can almost certainly be seen with the original 2016 BMW R5 Hommage bike, which was presented at the Concorso d’Eleganza Villa d’Este show.
This 2016 concept bike was the exact opposite of the latest design as it used an old 500cc boxer engine from a 1920s BMW but used a newly-designed frame.
So, to get a clear idea of where BMW is headed, take the frame design of the 2016 R5 Hommage with the engine of the two R18 concept bikes from this year and that should give a better idea of how this new cruiser will look in full production trim.
BMW has previously been honest about the need of the firm to re-enter the cruiser class in an effort to try and increase sales across lucrative markets like North America where bikes with the ‘feet forward’ riding position are dominant.
