The capacitor Does NOT increase voltage, rather it smooths it out, it is the rectifier that makes the unloaded voltage apear to be higher.
An A/C wave form has peaks, the RMS of an A/C source in a resistive load will be the average DC equivalent power delivered with is usually just above one cycles zero point cross over.
In over wo0rds the rectifier catches the peaks, the capacitor stores them and poof you get a higher Appearing Voltage put a load on it and measure through the RPM range again, I'd be willing to bet you'll see little if any voltage!
As stated be for you need to isolate the phases and the various speed windings, isolate them, and rectify them separately then feed them into the capacitor then finally to the load.
If you have not re-wound the stator you must use a 200V capacitor or you will blow the electrolytic up if a good enough gust cuases it to spin at a sufficient rate, or you need some other regulation method to ensure it never goes over the 63Uf (Which will happen if the dump load fails and they are not connected to the battery!)