If you own a Honda, you won't need to keep much spares. Most of the wear-out parts as brake pads, cables etc are still available from Honda. From my experience, when something breaks down, you never have spare. Or if you have it, it is still available or maybe even cheaper than what you paid for it. Furthermore, you are not going to need everything you keep a spare, so in the long term you end up paying more for the parts and storage than what you would pay for what you need, even if you have to pay an outrageous amount for it.
I only keep spares of what I have replaced, such as the sealed headlight etc. With my CB350 twin, unfortunately, I entered a "buying frenzy" because the bike was in a sorry state, so I bought many parts that seemed to look better. At the end, with elbow grease, the original parts looked much better, so I ended up paying in money and sweat. How many chances are there I will ever need another rocker cover? And I can't recover my money because, having paid the shipping from US, I will never be able to sell them for what I paid for them. I'm sentenced to keep them in my storage room forever, or until I need the space and I'm forced to throw them away. I even bought used control cables, and I ended up paying 10 bucks more to buy new reproductions.
With four classic bikes now, I can't afford to keep much spares. Fortunately, the two Hondas share many parts as blinkers etc, but even then, it's better to buy one if you break it than keep old ones. I bought used ones but now I'm seriously considering buying new ones because the used ones doesn't match the perfect new paint.
