The Bridge at Remagen

BMW R 12... R12 has a heavy frame like the KS750..this is in fact a BMW R61 from 1938-41..a rare item,less than 4,000 were built, Seems correct. Not R12, BMW R71 or a very early IMZ M72. It's easy to see because the front fork, gas tank, front and rear fender and frame (R12 is 100% different) There is a BMW R61 in this film too. The "Remagen" bridge is actually the similar looking bridge over the Vlatava River at Davle in Czechoslovakia..the tunnel in the film is a fake blasted by the film crew..during filming the scenes at the bridge a Russian MIG fighter and Russian helicopters appeared and buzzed a scene involving the M24 Chaffes. Chang Jiang CJ750 two details say Chang Jiang

Are you sure that it's a Chang Jiang and not a Soviet BMW copy? Were Chinese motorcycles available in COMECON countries during the 1960s?