2009 Milan Show: 2010 BMW R1200GS/Adventure and R1200RT

BMW's iconic Boxer Twin is in for a meaningful performance upgrade. Most of the BMW faithful consider the present sihc 1200 more than adequate, with power ranging from 105 to 122 horsepower. But BMW loves to engineer and had developed a rather sophisticated head design that finally allowed the use of dohc while retaining the elegant rear-facing-inlet, forward-facing exhaust.

This new valvetrain also allowed a degree of radial-valve geometry, a concept that has been highly regarded at BMW since the days of Ludwig Apfelbeck, who in the 1960s worked to produce a 2.0-liter four-cylinder engine for use in Formula Two racing cars. Apfelbeck's design never worked, but Munich still loves the idea. New dohc radial-valve heads were used in highly tuned R1200S endurance racers and then applied to the expensive, limited-production HP2 Sport, which became the most-powerful production Boxer ever.

Now those same heads are being fitted to the 1200cc Boxer that powers the 2010 R1200GS, R1200GS Adventure and R1200RT. All three models had a 105-hp version of the Boxer, and now they have been reinvigorated to 110 hp at 7750 rpm. In addition to the extra power, the new valvetrain pushes revs past the traditional 8000-rpm ceiling to 8500. Peak torque is now 88.5 foot-pounds at 6000 rpm.

The switch to dohc did not do all this by itself. It also opened the possibility of setting the intake and exhaust valves at a light radial angle, thus finding a little extra room to increase valve sizes from 36 to 39mm inlet and from 31 to 33mm exhaust. Valve lift has been increased to 10.8mm for all, from 10.54mm inlet and 9.26mm exhaust. Plus, the throttle bodies were enlarged from 47 to 50mm.

It's worth noting that with U.S.-average 91RON fuel, power most likely will drop to 98 hp. The first large-production models to receive the new heads, the R1200GS/Adventurer and the R1200RT, are otherwise substantially unchanged, the exception being a more protective windshield on the RT.