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BMW R90S Restoration Guide

BMW R90S /6 sport flagship boxer-twin (1973-1976, 898cc). Twin-disc front brake (R90S only), Bing 94 slide-carb pair, long-shaft 33/11 final-drive unit, and the 1973/74 mid-model-year ground-polarity switchover from positive to negative earth. Covers the factory contact-breaker points ignition on early 1973 /6 production AND the factory Hella electronic ignition retrofit kit on the late /6 1974-1976 production.