Designing/Predicting Output from Permanent Magnet Motorcycle Stators
Places to start:

Volts = 4.44 NfABmax.    

f frequency. N=turns. A = core cross sectional area. B=flux.
[Note that 4.44 = sqrt(2) x Pi] 

Imax is  limited by coil resistance and stator magnetic saturation. 

Flux can be measured with a flux meter / hall cell / ... .   

Airgap decrease increases flux. 

Pole field with good grade rare earth magnet can reach 1T at an airgap of about (magnet thickness)/2.
eg a 6mm thick rare earth magnet can give 1T at about 3mm airgap. 

Area A of coil or ~= of core. More area = longer wondings per given turns = more resistance and larger overall machine size. 

Delta Wye: Read it up. Lots on web.  


Delta Vout = coil voltage.   
Wye Vout = 2 coils at 120 degrees. 




Trial design:

If your windings are 2 layer they appear to have about 30 turns. 

Assume pole piece is 10mm x 10mm - you can measure this.
A = 0.01m x 0.01m = 1E-4 m^2  



Assume 1 T at pole surface - although you MAY get 2+ times this - and will probably get less. Deep-ends on magnets used, airgap, ... . 

Try at f = 1800 Rpm = 30 rps.
V = 4.44 N f A Bmax = 4.44 x 30 x 30 x 1E-4 x 1 = 0.4V per coil.
There are 18 coils. They are probably 3 phase connected (see 3 yellow wires AND usual practice).
6 x 0.4 = 2.4V per phase = too low.
Double revs = 4.8V.
Double core side = 4 x area = 19V
Change ....? :-).          

The above are per phase voltages.
For delta connection Vout = Vphase
For Wye connection, vout = Sqrt(3) x Vphase. 
So Vout in above example = 1.732 x the values given.

ie the above values are "in the order of right" and the final result depends on changing the above assumptions to actual values.