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 A flathead engine, also known as a sidevalve engine''American Rodder'', 6/94, pp.45 & 93. or valve-in-block engine is an internal combustion engine with its poppet valves contained within the engine block, instead of in the cylinder head, as ...

single-cylinder A single-cylinder engine, sometimes called a thumper, is a piston engine with one cylinder. This engine is often used for motorcycles, motor scooters, go-karts, all-terrain vehicles, radio-controlled vehicles, portable tools and garden machinery ( ...

powered bikes.Erwin Tragatsch; Ash, Kevin. ''The New Illustrated Encyclopedia of Motorcycles'', Quantum Publishing, London, 2000 {{Cite web , last=ManxNorton.com , title=Adria Motorcycles , url=https://cybermotorcycle.com/euro/brands/adria.htm , access-date=2022-12-07 , website=Classic Motorcycles at Sheldon's Emu , language=en

References

Motorcycle manufacturers of Germany