Unless he is getting a cruiser I always advise against used sport bikes. You have no idea how long they spent on 1 wheel and being over revved. A used sport bike with 10k miles may have the equivalent of 50k in aggressive riding but still look good. They are not cheap to fix by any stretch of the imagination.
Jap cruisers: If it is not smoking and overheating just look at tires, cables, general condition. They run forever, just shop price and style. Most Japan Inc. bikes get their cosmetics abused and the chrome bits seem to fail in the appearance department. In short, the bike falls apart around the motor that never seems to quit, and just starts to look old and worn out.
