Adria (motorcycle) explained

The Adria company were better known for their motor vehicle and boat engines, but between 1912 and 1928 they built a range of 276cc, 282cc, 294cc and 346cc side-valve single-cylinder powered bikes.^{[1] [2]}

References

1. Erwin Tragatsch; Ash, Kevin. The New Illustrated Encyclopedia of Motorcycles, Quantum Publishing, London, 2000
2. Web site: ManxNorton.com . Adria Motorcycles . 2022-12-07 . Classic Motorcycles at Sheldon's Emu . en.