I recently figured out that the stator assembly on my 72 AT2 was not producing voltage up to the regulator.  I found a stator on ebay for a 1970 model. Parts number are the same so I purchased it.  Upon inspection, it was determined that the stator assembly between the 70 model and 72 model were not the same.  Diameter where the armature fits in on the 70 model was considerably smaller than the 72 model.  So, I purchased an armature for a 70 model, figuring that would work.  Well, the governor assembly from the 72 doesn't match up.  Next, I found a governor assembly from a 70 model and installed that.  Mind you, all part numbers from 70, 71, 72, and 73 are the same.  After all parts were installed, bike starts, runs, and produces 14.25 volts up to the regulator.  Problem solved you would think.  But, cranking speed of the 70 setup is not as fast as the original 72 setup.  I can live with this setup, but, my questions are these.  One, why would the part numbers show the same for all the models when they are obviously not?  And does anyone know if it is possible to rebuild/rewind the shunts on the stator of the 72 model?  Sorry for being so long winded, but anything shorter would probably be more confusing.

If you're talking the "assembly" part number being the same it's because you would upgrade a older bike with the new updated assembly.

I'm not sure exactly when the larger generator was first used... but it was probably on the AT2. The larger version was used right through the 1976 DT125c models with generator/starter.

Individual parts for armature, stator, governor, etc. are different as you found out. If you look carefully at the online AT2 parts list, they show TWO numbers for each part... some are listed under "0" right at the beginning of the list.

Parts lists were originally shared among similar models. If you had an original parts book or fiche and not the online version that lost the model charts, it probably would have been clear. You just always need to look at the online parts lists carefully and if you see 2 part numbers with the same description, be very careful.

And unfortunately sometimes the online lists are missing part numbers completely.

If you can find an electric motor shop they might be able to repair your original unit? It's a slightly unusual design with both self-energizing generator windings and starter motor windings in the same unit so you should probably tell them that.

Or look for an assembly off a 74-76 DT125... for sure they had the upgraded design but of course someone could have swapped to an early AT unit like you did... so get measurements and/or pay careful attention to the visual differences... like aren't the points different?

Thankyou very much for the info.  This really clarifies a lot  of my questions.  I'm going to contact some companies that deal in electric motors, alternators,etc. and see if something can be done with the non charging stator. I expect big bucks for a repair.  I'll also keep an eye out for another unit.  Thanks again. 

Hi Robert,  
 you can use an ohmmeter to check the resistance through the windings and see if they are good .