The yellow hose is the fuel overflow from the bottom of the fuel tank that redirects any fuel spillage within the fuel cap compartment down to the ground. Mine, also a CB750K8, is routed from under the tank, over the frame rail next to thr rear tank rubber mount, then down directly in front of the battery (following the battery vent tube). The splice in the tube ends up at the top front of the battery to permit tank removal without pulling the entire hose out.
The smaller bracket mounts inside the alternator stator cover to hold the field and stator wires out of harms way, away from the moving parts.
The black hose looks to be a vent or overflow tube, I'd have to look around to find out which one.
As for the larger, shiny bracket, it looks very familiar but I can't pin it down. I'm thinking it mounts down around the centerstand, behind the rear of the engine to capture one or more overflow/vent tubes to hold it (them) out of harms way. It's awfully clean though, I'm wondering if it might be from inside the engine case.
I'll repost if I find out for sure.
