To run a 2.5 KW DC shunt generator, a DC motor with an appropriate horsepower rating must be determined, factoring in motor efficiency and losses. The conversation highlights the importance of understanding the conversion between horsepower and kilowatts. Additionally, the discussion raises questions about the power source for the motor and the load that the generator will be supplying. These considerations are crucial for accurately sizing the motor to ensure optimal performance. Overall, the efficiency and application context are key to determining the necessary motor specifications.