Workshop Walkthrough

BSA Gold Star DOHC single-cylinder — four-stage animated walkthrough

A four-stage preview of a BSA Gold Star DOHC single-cylinder restoration. The teardown stage walks the shim-under-bucket valve spring compressor sequence and three-stage reverse-torque head lift. The engine stage plays the full DOHC top-end procedure on-canvas. The wiring stage previews the three-system Lucas / BTH electrical split (BTH magdyno / E3L + magneto / RM13 alternator). The reassembly stage ends at the cold shim-under-bucket valve-clearance set.

Teardown: Drain the engine sump and the primary chaincase separately, mark the duplex primary chain orientation to the camshaft pinion and the right-side timing chest, release the cam cover cap-screws in a two-stage cross pattern (past 10 ft-lb cracks the cast-alloy flange), cap the intake and exhaust ports with painter's tape BEFORE lifting the alloy head, then lift the DOHC single-cylinder head in the three-stage reverse-torque sequence (25 -> 12 -> 0 ft-lb).