Very interesting. I just acquired a 1982 R100 (Says that in the Serial Number and on the side covers. It has the CS fairing and is painted the CS Black with pin striping throughout. This one has a stainless 2 into 1 exhaust system, some kind of after market shocks with red coils on the bottom of the coil stack, bags and a Corbin seat. An absolute beauty of a bike that I got out of a shed that had stuff piled on it, covered in 5 years of dust and grime (but didn't damage it, other than one chip out of the front fender paint and one hinge on the Corbin seat was missing. Stunning bike once I got it cleaned up!
Anyway, the first four numbers of the serial are 6175. Anyone got an idea of whether this is one of the legendary CS models? Doesn't much matter as it's going to get a Canadian Collector Plate and be recreationally driven.