Lithuanian Motorbike Mystery, part 2
WHAT MOTORCYCLE MAKE MODEL??
see original photo here:
Maybe this one?
eysink alpenjager JAP engine
Here is the JAP engine inside of an HDR - HD70
you see, the "second cylinder" is where the exhaust pipe is connected!
the engine is therefore a JAP,
JA Prestwich Industries, was an English engineering company named after founder John Alfred Prestwich, which produced cinematographic equipment, internal combustion engines (for which the company was generally abbreviated to "J.A.P."), and other examples of precision engineering.
From 1904 to 1908 complete motorcycles were produced  from the development of the first overhead valve motorcycle engine to be produced in the UK. 
After that the factory concentrated on supplying its engines to other manufacturers, including Brough Superior, Triumph Motorcycles, A. J. Stevens & Co. Ltd, and HRD Motorcycles, the forerunner of Vincent Motorcycles. Machines that incorporated its engines included the AJS Model D, fabricated for the Russians in the First World War.
JAP exported significant numbers of engines to foreign motorcycle manufacturers including Dresch and Terrot in France, and Ardie, Hecker and Tornax in Germany.
500 cc JAP sports sidevalve
like the one used in TORNAX bike
Ardie was a company in Nürnberg, Germany that manufactured motorcycles from 1919 until 1958. The company's name derives from that of its founder, Arno Dietrich.
At first Ardie made motorcycles with its own 288cc and 304cc single cylinder two-stroke engines. In 1925 the company switched to using engines from JAP in London, England.
or how about a TERROT
ARDIE Stumble It!