I am about to buy my first (xs750 1977 Yamaha) this Saturday. I've seen the bike run but the seller says it needs a battery and a tune up. I just talked to a buddy and realized I don't want to pay a few hundred for a tune up if I don't have too. What all would a shop do to this bike and how much could I do without killing myself or destroying the bike? What would I need to do to this 40 year old bike that has a few thousand miles on it and has been in storage for several years and would I be able to do it?