Following on an earlier post, my '84 serial number is 617XXXX, putting it outside the 618XXXX range for a true U.S. "CS" according to BMW SN records, yet mine appears factory stock with an S Fairing, all matching factory polaris and blue pinstriping, dual brakes, oil cooler etc. Side covers say R100 and the SN# puts it in the block with late US R100/7 bikes, not CS. To further add to confusion, the original owner's manual entry by the owner identifies the bike (purchased in Modesto, CA) as a R100CS. If not a "CS", did the factory offer R100's with a matched S fairing etc.? As a practical matter, what if any difference was there engine/performance wise, if any in '84 between a CS and a standard R100? Thanks for any clarification (I have seen another '84 with S Fairing in same paint scheme looking exactly like mine with R100 on the sidecovers, reinforcing a view that my bike is factory stock, whatever it is).