either russian ural or dpner or a 40's bmw flathead. Really they are all the same engine since the russians just absconded with the factory during WWII and have continued to make them since.
Surprisingly there is a big chopper movement in the former soviet union. The Horse did an aritcle about it 2 years ago. Most of the bikes are old WWII harleys but there were some dnepr and urals as well. They are pretty hardcore riding bikes I wouln't even call death traps here in the states.
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