Russian Motorcycle Comparisons:

BMW R-71: 1938-1941, 3,458 est. production
This is the "Oma" of most of these bikes.

BMW R-75: 1940-1945, 17,500 est. production
This replaced the R71 and dominated production for the Axis. Note the head changes.

IMZ M-72: 1941-1960, est. production
Based straight off the R71, still copied today.

Harley Davidson XA: 1942-1943, 1,011 est. production
Rare example of HD's flat twin army mode, their only attempt at a flat twin since the 1920's W model.

KMZ K-750: 1959-1963, est. production unknown
This bike changed to a swingarm frame and was the eventual design replacement of the M72.

Ural M66: 1968-1975(?), est. production unknown
Marked the plant's evolution to the 650 engines and more dedicated to the offroad design.

Chang Jiang CJ750: 1951-current
They still replicate the R71. Kind of. Cheap and worth considering but reports are that machining is poor.

Ural Tourist 650: Current
The new Urals have their own following. They're inexpensive and relatively reliable, but still regarded as a machine for people who are comfortable with wrenches.

Dnepr MT-11: 1980-current
Same thing I said about the new Urals, just add a bit more wrenching.