Does the smoke start in the first couple of seconds, or after it runs for a minute or two? Are the brushes worn or the springs that push them in damaged? Could you have gotten some lubricant or cleaner in the motor windings when you replaced the bearing? Are all the housing parts, bolts, screws, wire nuts, etc. tight and in place? Is any small part rubbing against a moving part? Any damage, scratches, debris in the motor's windings? Wiring smoke has a distinctive smell, is that what you smell? If you run it this way, does the fuse blow on that house circuit? Is there a short in the on/off switch? Does the speed control work? Any sign of a short on the speed control circuit, burned spots for example? If you take it apart and sniff the different parts, does one have a stronger aroma of smoke than the others? Are there any burned or melted spots where the power cord attaches to the router? Sometimes a stray strand or two of braided wire will short out Is there any lateral movement or play in the motor shaft, particularly at the end where the old bearing is located? All these things are where I'd start trouble shooting.
The more I do, the less I accomplish.