Originally Posted by lucky6600
Comparing to other 980cc engine, how did BMW actually do to detune the engine to make it smoother?
Especially with the same engine block, pistons and 40 mm Bing. Only thing that I could think of would be the more fancy but more restricted exhaust to meet the emission.
The r100r has 32mm bings, not 40s. The pistons are not the same as earlier higher output R100s. They have a lower compression ratio of 8.5:1 compared to 9.5:1 in the higher output motors. The heads also changed from large port/valve in the in earlier models to smaller ports and valves in the later models. The exhaust doesn't do anything to meet emissions. There's no cat. Jetting also got leaner from earlier to later models.