BMW R-Series Gets Revised Motor with DOHC

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The rumors appear to be true, and the BMW R series is getting an update to its motor for 2010. Maintaining its existing 1,170cc displacement, the most notable change to BMW’s flat boxer motor is a dual-overhead camshaft (DOHC) cylinder head setup, which was previously only seen on the HP2 Sport.

With the bore and stroke staying the same for 2010, the R lineup will continue to use the same 101 x 73mm cylinders, making a total of 1,170cc’s. The real changes and improvements come from the new cylinder head design. The DOHC design features two chain-driven camshafts, with each camshaft controlling both an intake and exhaust valve in the radial four-valve head.

While the cylinder hasn’t changed, the valves have, and will come with an increased diameter size (intake: 1.42-1.54 inches;  exhaust: 1.22-1.30 inches). The valves will also have an increased lift, while maintaining the same 12:1 compression ratio. Lastly, the combustion chamber shape has been modified, and now employees the use of red-designed cast-aluminum pistons, which will also make better use of the redesigned air intake manifolds.

All of this means a more powerful and higher-revving motor. Expect to see 110hp @ 7750 rpm (+5hp increase) at the crank, and peak torque at 88lb•ft  @ 6000 rpm (+3lb•ft). The motor’s redline has also been increased by 500rpm, which raises it to 8,500 rpm’s.

The new Boxer motor is the core upgrade to the three 2010 R-series machines announced by BMW: the 2010 BMW R1200GS, 2010 BMW R1200GS Adventure, and 2010 BMW R1200RT.

Source: BMW