To evaluate the characteristics of induction motors by using an increasing moment of inertia technique has an advantage more than other methods which are presented before. Because this method give the characteristics in all speed ranges and ease to accomplish. Since the investigated motors have small size, the test under rated voltage can be performed. The increasing moment of inertia technique is used to gain the accelerating time causing the depletion of the electrical transient and to give the appropriate point of data for analyzing and calculating. Since there is the difficulty for locking the flywheel to the shaft of motor and the different size of shaft due to size of motor, locking the flywheel directly to the shaft of motor is not recommended. So the shaft with constant diameter for coupling the flywheel which one end is coupled to the shaft of motor and the another end is coupled to the flywheel is necessary for this test.