Regulator/ Rectifier swap

[kelso]

I am using a 78 motor with a pamco and wiring from scratch. I need a reg/rec and from what I see they are separate on the 78. There is a reg/rec on my 1980 that i'd like to use. I was trying to figure out if there were any issues with using the one off of the 80 and I noticed that the reg/recs that mikesxs sells are different part numbers for earlier and later years (pre and post 79). I am thinking that this is only because of the wiring setup on a stock bike and that it shouldn't matter since I am starting from scratch. Any thoughts?


Mikesxs reg/rec for 1980-84 is part #24-2087 and it says that it is not for use with older models.


78-79 models are part #24-2089 and it has this disclaimer

Note:
This Rectifier/Regulator is sold only for use with stock 1970-79 wire harnesses.
If you are purchasing it for use on a chopper or custom, please note that we can't
accept returns for any reason due to the possibility of it being incorrectly installed.

 

[Grinder]

Have a look here at Pete's explanation.

http://www.xs650.com/forum/showthread.php?t=15141&highlight=ungrounding+brush

 

[DogBunny]

Edit................

 

[kelso]

According to the link to the other thread that Grinder posted I would need to unground my 78 motor with nylon screws.
Retiredgentleman wrote "The diagram you posted does not tell the complete story. That diagram ( unground the 3 screws) is correct only if you are using a 80 to 83 type of regulator with a 70 to 79 stator/brush alternator. The 70 to 79 years all had one grounded brush, whereas the 80 to 83 years do not."

So unless I am missing something the regulator from my 80 was used with an ungrounded stator while the 78 motor is grounded and I would need to unground the 78 in order to work with the reg/rec from the 80?
Dogbunny I know that you are saying to do the opposite, am I thinking incorrectly about this?

 

[DogBunny]

Yeah, I was wrong. You need to get 3 nylon screws and un-ground the inner brush with them. Then connect the wire that goes to that brush to switched (keyed) power.
http://www.amckayltd.com/wiring9.jpg
Wire your combo reg/rec like in the above diagram.

 

[kelso]

Thanks DB, I appreciate you clearing that up. Now I've got a plan