Using the Comer C - 52 engine is easy. First, make sure it's properly installed in your 50cc kid kart. Check the clutch, carburetor, and muffler to ensure they're all in good working order before starting the engine. When starting, follow the standard procedures for your kart. As for maintenance, regularly check the oil level and change the oil as recommended. Keep the carburetor clean to ensure proper fuel - air mixture. Also, inspect the muffler for any damage or blockages. Always store the engine in a dry place to prevent rust and corrosion. And remember, if you have any problems, consult a professional.