it is indeed the Simson RS 250/6. Therefore you have earned the two-point bonus first
To the different versions of the AWO/Simson RS: RS 250/5, this single-cylinder version is accompanied by another small contribution in a moment.
RS 250/6: First version had a triangular chain driven camshafts, like the single-version. There was a late version with king-shaft-driven inlet-camshaft and connection through spur-gears to the outlet-camshaft. There should also be experiments with desmodromic valve control.
RS 250/7: This was the last Version of Somson 4-stroke racers. So, there could also be used the king-shaft / spur-gears version of camshaft driving. But I only found pictures with pure chain-drive.