I've stored my 914-6 for years outside. Couple of hints. Use bungee cords to tension the cover and prevent flapping. Extra grommets can be added.
https://www.amazon.com/s?k=1%2F2+inch+brass+grommets&crid=ZUR97G9P5KE&sprefix=1%2F2+inch+brass+%2Caps%2C138&ref=nb_sb_ss_ts-doa-p_9_15 I sometimes also use 9x12 plastic drop cloth under the cover to give extra protection to cab and engine
Works for me