Inside a DC motor for RC, an electromagnetic coil is attracted to a permanent magnet within the magnetic motor assembly, and this attraction causes the motor to rotate. When electrical power is absent, the wire loses its magnetic qualities and the motor stops accordingly.
The newer generation of brushed 540 silver can motor comes with a strong magnet feature. The magnet of the motor is so strong that the torque is significantly improved, allowing the car to run much faster in offroad condition. Therefore, when buying your next brushed motor, always ask the shop whether the motor is one with strong magnet. It is cheap and powerful. In my opinion, a strong magnet silver performs much better than those expensive Tamiya sports tuned ones.
This vid shows a 14T silver can which was not originally designed for RC. The shaft is not D cut so you must cut the shaft yourself.
The vid shows a Kyosho 1:10 belt drive 4WD with another cheap 14T silver can clone. The model number is 540-8514.