If the battery or battery pack is not the problem, there are other possibilities. One possibility is that the carburetor on your 50cc scooter may be defective. If you notice that your e-scooter isn't going as fast as it used to, and the carburetor seems to be working correctly, it's a good idea to check it out. Many times, small issues with the carburetor can cause an e-scooter to not go as fast as it should. If you find that your carburetor is defective, you can replace it with a new one.