Is it correct that the speed limit for motorcycles on expressways varies based on engine displacement?

The correct answer highlights a significant regulation regarding motorcycles and expressway access in Japan. In Japan, motorcycles under a certain engine displacement (in this case, 125 cc) are generally prohibited from using expressways. This restriction exists because smaller motorcycles, often viewed as less powerful and potentially less stable at higher speeds, are not permitted on high-speed roadways designed for larger vehicles.

While larger motorcycles, typically over 125 cc, may have higher speed limits due to their ability to maintain stability and safety at faster speeds, the critical aspect here is the regulation preventing smaller motorcycles from even accessing expressways in the first place. As a result, this choice emphasizes the rules surrounding motorcycle displacement and its implications on road usage, aligning with traffic safety standards in Japan.