Well, Im tring to find the procedure to testing the Rectifier.

Battery is good, Stator looked ok when I replaced the side cover ( bought the bike as a wrecked unit.)

BIke will start and run. And when I check the battery the voltage will go up and down with the bike rpm but slowly gets lower and lower.

If I disconnect the battery while the bike is running, it will run for 3 seconds or so then dead.


Any help is appreciated.

 

Disconnecting the battery while the bike is running will blow the shyte out of the rectifier. If it wasn't pooched before it will be now. That is a big no no. I'd order an new rectifier right away.
When you remove the battery from the circuit you cause a voltage spike. The spike will find a path to chassis ground...usually by shorting out a diode on the rectifier. The symptoms of gradually loosing voltage in the battery are consistant with a bad diode. Hopefully the insulation on the stator was strong enough to withstand the spike.
If these bikes ran a generator disconnecting the battery would not cause the bike to stall, but it is an alternator.