A photographer friend bought one and left it unridden in his studio.
Zero miles and Zero engine starts and 2 years later it started leaking oil.
So I know they will require gaskets, even if you don't use them.

You will need a big bag of oil dry to park the bike on top of while in your garage.

hey its not to much maintenance its a lot better that a quad but every twice a year chage your air filter and and get you oil changed every about 3000 miles man but other wise keep clean engine and bike and it will laste for ever on quads we have to change oil every 400 hours if we ride a lot

tighten and torque all critical fasteners, its a problem with all HD's, bolts and nuts come loose, its important to tighten using locktite and the proper torque ( over-tighten will damage the fasteners )
tire air pressure is also very critical, every-time I get my bikes out i check the tire pressure, a 5 psi difference could mean a difference between life and death.
proper oil level check, many people don't know the proper way to check the oil level, you must allow the bike to sit level and not run for at least 5 mins to check the proper oil level, many people make the mistake over-filling their oil