For a 50cc snowmobile, which is typically designed for youth or beginners, you must prioritize engine reliability and safety features. Ensure the engine is a 4-stroke design for easier maintenance and lower emissions, or a high-quality 2-stroke if power-to-weight ratio is critical. Key specs include a governor or speed limiter to control maximum velocity, emergency kill switches (tether cords), and a reinforced steel or aluminum chassis to withstand impact. Verify that the track material is high-density rubber with adequate lugs for traction on packed snow.