I think any storage should be preceded with a good cleaning.
Keeping them inside is a good idea but I wouldn't recommend sealing them up. Simply wrapping them in a old towel ought to suffice.
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In oher words, if it is climate controlled (inside a heated home), then you don't want them able to hold moister in, let them breath. Makes sense. I figure these will be out in the unheated garage. I think I might just go as far as buying some desicant from HF and do the job right, maybe even some cualking around the lid to make it really air tight.
I was thinking spray lithum grease. I'm not aware of any grease hardening? WD40 dries, and since this is long term storage, I would be more inclind to use oil, something to "seal" the metal parts from rust/corrosion.
I am toying with the idea of a rebuild, but if they didn't need it before, why do it now, when they are going into storage? I was going to do it as a service thing, rebuild the spares, swap out the ones in the bike, then rebuild the bikes and store them.
How much are the parts for a complete overhaul kit?