There are rumors that Sachs will return, but that's just rumors. They make new mopeds, but I don't know why nobody imports them...
Sachs are one of the more popular motors on mopeds, I think there are around 8 different brands that use them, Hercules is the biggest after Sachs itself, but there are several others.
On the whole they are smooth and reliable, but not too many performance parts out there.
You have a 504 motor, it's the same as the 505, but the pedals are not attached to the case. If you want to find out which version, look at the metal plate on the top, over your flywheel (right side while sitting on it).
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