* In the UK, for example, riders aged 19 or over can ride a motorcycle with an engine size of up to 125cc without any special restrictions or additional training. To ride a motorcycle with a larger engine, riders under the age of 24 must pass a motorcycle test, which includes a theory test and a practical test.
* In the US, regulations on motorcycle engine size and rider age are determined at the state level, so it's important to check the specific laws in your state. In many states, riders under a certain age (typically 16-18) may be required to take a safety course or obtain a learner's permit before they can operate a motorcycle. The engine size restrictions for young riders may also vary from state to state, and could range from 50cc to 250cc.
To obtain the most accurate and up-to-date information, it is always recommended to refer to the official government or transportation authority websites for the specific country or region you are interested in.
