The four-valve oil-head update of the traditional boxer twin was a gutsy move on BMW's part to keep the design competitive in the marketplace, but I think that it was the last hurrah. I expected the next iteration of the boxer to be water-cooled, but instead BMW increased the displacement and added more complexity in the form of balance shafts. Personally, I think that BMW should have refined the twin by decreasing the displacement slightly, adding water-cooling and giving up on chasing horsepower, but they didn't ask me. Without going into a long technical discussion I think that the good reasons for the traditional BMW configuration (air-cooled flat twin with shaft drive) are no longer relevant. Other designs are easier (and cheaper) to manufacture, more aerodynamic, and lend themselves to higher specific output. However, just as Harley-Davidson means an air-cooled, 45 degree V-Twin, so does BMW mean an air-cooled, flat-twin to many people. BMW has managed to keep the design competitive in a marketplace that demands ever increasing horsepower, but just barely.So, would it be safe to assume that you believe that the Boxer design itself has reached, and perhaps gone past its sell-by-date?
As to the original focus of this thread - oil consumption - I suspect that normal manufacturing variations in valve-guide tolerances have a lot to do with why some engines consume more oil than others.
Peter '73 R75/5, '04 R1150RA
to date I've owned a 2001 FXDXT, a 2002 FLHTC, a 2003 XB9R(Buell but still basically a Harley), a 2004 VRSCA, a 2005 XL1200C, and now a 2006 VRSCD. Not one of them has developed an oil leak. We put about 5000 miles on each of them before I traded them back in on something else. (I get a discount once a year) I never had to add oil to any of them. Even the V-Rods which are known to eat a little oil till theyre broke in. Also, according to warranty claim data, we arent too far below Honda anymore. OK, thats all for my public service announcement!
