regular motorcycle
Used on street signs and in traffic regulations to distinguish standard motorcycles from mopeds, scooters, or other two-wheeled vehicles. Not a general conversational term.
This sign prohibits regular motorcycles.
自動二輪車 is the full formal term for a motorcycle; 自二輪 is an abbreviation used mainly on signs.
Abbreviation of 自動二輪車 (じどうにりんしゃ), a regular motorcycle.