What you experienced was back EMF from the starter. If you run current through a coil of wire (inductor) and then suddenly remove the current source the collapsing electric field produces a much higher voltage the the original supply voltage. This is how the ignition coil works, but the efect is present in all circuits with an inductor. I am surprised Mezo, that you were not aware of that. Probably day dreaming in theory class all those years ago. You have a copy of the workshop manual. There is a section that details trouble shooting the starter circuit. Refer to that Regarding the single spark from the ignition coil. Many CDI ignitions systems will spark the coil once on ignition turn on and once on ignition turn off. This is normal and prove the coil and HT lead are working. If you are not getting sparks as you turn the engine then you need to trouble shoot the ignition pickup circuit and also the coil NEGATIVE. Remember that the coil negative is grounded by kill switch, ignition switch, side stand and clutch switches. Plenty of places to go wrong. Dont make me drive up there and set a new LDD record. LDD = Long distance driving.