How much will Harley Davidson maintenance cost?

That is a big question. It depends on many things.

What year is the bike?

How do you plan to ride it? (Long ridges, mountains, etc.

Did you buy it new?

If it's new or newer is the service plan available?

Do you plan to do the maintenance yourself?

Do you plan to have a dealer do all maintenance?

The short answer is

If you do it yourself by buying the manual and purchasing parts it will cost you the following.

Time

$150+ for a motorcycle lift ( I recommend this.)

$150+ for tools, (sockets, possibly an impact wrench, etc.)

Basic mechanical know how.

In this case I would say yearly maintenance will cost on average $150-500/year not including the tools

If you plan on having Harley do it, expect the following.

$75 Approx. for shop time per hour

Parts+shop mark up.

In this case expect yearly maintenance to exceed $500+

This is accounting for a tire, oil changes and your mileage based services.