I'm rebuilding a 1973 R60/5. It will be a pleasure bike, but as my only bike, I can also see it going to the track from time to time. It's been a long time since I did track days and I miss it. I don't mind some added vibration (I used to ride KTM singles ). Other than that, what are the considerations towards and against a lightened flywheel? Does it have a large effect on engine response? I'm looking specifically at San Jose BMW's CC Products modification that reduces weight by 36%. I should mention that this will add about a month and a few hundred dollars to my project, but the engine and tranny are out, and if I'm ever going to do this, I'd like to do it now. Thanks in advance for any input.