You can still buy small quantities of carbide for lamp use.
I stand corrected if it was lumps, maybe the modern stuff is powder.
Can't remember where I saw it available, someone in the vintage or veteran club could probably advise. Modaks in Mlbourne may well have it. ?
Lamps were generally nickel plated - you see car lamps in brass, but bikes ones always seem to be nickel ?. Only bicycle lamps had the generator integrated with the lamp, the generator on a motorcycle was a separate unit. The plumbing was done by rubber hoses, exactly like the hose used in acetylene cutting torches.
BTW, until recently there was an old giant acetylene generator for oxy cutting in an old backyard of my youth, but it seems to have gone in a cleanup. It was already beyond functional, to my memory - wonder how old it was?. None of this cylinder rental/hire charge nonsense.....
hth.