RTF doesn't mean Ready To Fly.[:@] It means Ready To Fix. OK, it's not that bad but whenever you buy a plane, new or used, always assume the worst and go over it thoroughly and check EVERY nut, bolt and screw for security. Loose hardware is not uncommon. Don't forget what the labor rate is in China and Viet Nam. Would YOU do good work for what they are paid either?

Ringed engines get broke in "sloppy rich" like nickj said but engines like yours do not have a ring and should be broke in rich but not extremely rich. Part of the break-in requires the engine to get to full operating temp which it can't do if running too rich.