Hmmm, first of all, how many Volts (AC) come from the generator? Please check all three wires
a) against ground
b) against each other
If you find an AC voltage higher than, well, let's say, 60 V at any rate, your generator is fine.
Next step:
Either try to find another Hayabusa and grab its rectifier for testing purposes or try to get any other rectifier, e.g. from Yamaha R1, Suzuki GSXR 1100, or whatever kind of rectifier you can find. They all work the same way:
The incoming AC voltage is being rectified to DC voltage by using 6 diodes. Now the prob is that the incoming voltage is only depending on the engine's rpms and it'll rise "endlessly". This would give an output voltage much higher than the max of 14,5 V. To get it suppressed you have built-in three short-cicuiting thyristors which connect the voltage to ground as soon as the output voltage gets higher than 14,5 V. Therefor the generator's input voltage drops down under the 14,5 V (into saturation). The thyristors then disconnect the input voltage from ground and the generator's voltage rises again until the game starts again.
Means, the output voltage is more or less "produced" in the same way, no matter what kind of bike you take. All bikes with external rectifier do it the same way and therefor you can use any bike's rectifier.
Btw. the way how the rectifier "regulates" the output voltage gives you the reason why that stuff is getting so hot while working.
O'right, let's assume you found another rectifier... how to handle it?
They ALL have at least three input wires (with the same color) and one output wire (different color to the three above, mostly red). Some of them have an additional ground wire, some not. If not, the rectifier's housing is the ground wire and must be connected to ground.
Just connect your three generator cables to the three same-colored cables on the rectifier (you can't mix them up, it doesn't matter which is connected to which as long as you only connect same color to same color
)
Ok, now you have at least one cable left. If so, this is the "battery +" cable, connect it to your DC voltmeter. Bolt on the rectifier so it is grounded.
If you have a seperate ground cable coming from the rectifier, connect it either somewhere to ground or directly to "battery -".
Gentleman, start your engine and see how many volts you find there.
It should be somewhere between 13,8 to 14,5 V.
Come back with your findings and we'll see, ok?
Hope I could help...
D1