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Motorcycle News, Editorials, Product Reviews and Bike Reviews

Radical Bore/Stroke Ratio of BMW S1000RR Superbike Points to High Revs

The bore/stroke ratio of BMW’s superbike, announced Tuesday, here on MD, of 1.6:1 indicates this bike is made to rev. Indeed, the specifications provided by BMW include peak horsepower achieved at over 14,000 rpm. This is 600cc territory!

No other production, homologated superbike we are aware of, Japanese or European, has such a radical short-stroke engine design as the new BMW. Indeed, even smaller displacement sportbikes, such as supersport machines and Ducati’s 848 are less “oversquare” with bore/stroke ratios of 1.58:1 or less.

We have tried to determine the manner in which BMW is controlling valve opening on this new superbike, but have not received that information from BMW at this point. Information on the production model is still a couple of months away. With such a short stroke, it is possible BMW will be using variable valve timing, variable trumpet length or some other system (or a combination thereof) to develop a broader spread of power. Stay tuned.