Workshop Walkthrough

BMW R90S boxer-twin — four-stage animated walkthrough

A four-stage preview of a BMW R90S /6 boxer-twin restoration. The teardown stage walks the separated engine / primary-case drain, the auto-advance plate orientation mark, and the three-stage reverse-torque head lift. The engine stage plays the full boxer top-end service procedure on-canvas. The wiring stage previews /6 electrical work, including the 1973/74 mid-model-year ground-polarity switchover. The reassembly stage ends at the cold valve clearance set.

Teardown: Drain engine and primary-case lubricant separately on the R90S boxer-twin, mark the auto-advance plate orientation to the crankcase pinion, and lift both cylinder heads in the three-stage reverse-torque sequence (32 -> 26 -> 16 N-m). Cap both intake and right-side exhaust ports before any shim work -- the R90S right-side plug is on the head, not the case.