There is no universal body that hands out ratings for mopeds and motor scooters. Though it would be nice if there was some big, governing body that oversaw all of the different mopeds being produced every year. Especially since there are at least thirty different companies that manufacture mopeds, and even more than produce and sell motor scooters, which are often confused or conflated with mopeds. Since there is no larger body to hand out ratings and warn consumers about which mopeds are poor quality and which are better quality, you might need to rely on other sources to get your moped ratings. These other sources include magazines that focus on motor sports and motor sport vehicles, enthusiasts who are dedicated to promoting mopeds and motor scooters to new riders as well as attracting new people to their hobby. There are also websites that rate different mopeds and motor scooters according to different criteria, including size, speed, mileage, and the type of the engine.
If you are searching for ratings because you are searching for the best moped available, the best way to do your research is to look into different magazines and discussion forums. People who are not pleased with their mopeds will make their opinions known without much prompting, and so if you can find moped forums, websites, review sites, and discussion sites, you should be able to get a good sense of the ratings. It is always good to get a second and third opinion on a major purchase before you take the final step. Extra education never hurt anybody.
Moped ratings consistently list Yamaha mopeds among the best models available.
Research moped ratings before purchasing from moped dealers.