We'll see how this works... it's the wiring diagram in PDF format. Use the freely available Adobe acrobat viewer/reader. This is the diagram for 1980 Sachs and later. Earlier ones were different in various ways, but there's still useful information in here.
NOTE! One thing that isn't on the diagram is the points & condensor & and the coils inside the magneto...
1) Yellow wire connects to a lone coil inside the magneto.
2) Blue w/ Black connects to the other coil inside the magneto.
3) Blue comes from the points.
4) On my bike there's either a white or black (can't remember which) wire that goes from the points to the condensor, and then the case of the condensor is grounded.