Questions to think about:
Have you ever run a business before as an owner or primary manager?
Will your market support a bike store for older bikes? Is the cost of inventory worth the amount of business in the area, or is mail order very efficient?
How will you finance your business? Do you know the approximate monthly cost and the break even point for sales? Do you know how to balance your books and create business plans that the bank will accept for financing?
Do you have mechanical aptitude and experience with older motorcycles? Would you be able to assist your customers?
Why should I, as an owner of an older Harley, come to your store versus mail order or the other bike shop, which I assume could special order my part?
Have you done retail work before? Do you like it?
Have you considered other businesses which might have a better margin? Including electric vehicles, bicycles, scooters, and so on? Do you realize that smaller vehicles, scooters, motorcycles and so on will become very popular as the price of oil continues to soar. (query "peak oil")