The Lego Technic 857 Motorcycle With Sidecar. This was an unusual set, as there were instructions for a second build, The Chopper (middle left picture) - was this the only set that
857 Motorcycle - LEGO instructions and catalogs library
LEGO Set 857-1 Motorbike with Sidecar (1979 Technic > Expert Builder) | Rebrickable - Build with LEGO