Help with a 71 Cub Electrical System

I bought a used 1971 IH Cub serial number 238035-J a couple of years ago. I have been using to cultivate a small garden on our farm. I had trouble getting it started the other day and found that the wiring harness had finally gone bad. The tractor has a 6 volt battery installed in it. But the dealer said the serial number is for a 12 volt system. Looking at the wiring it matches the 12 volt system in my owners manual. The generator has a 12 volt tag on it. I am confused, I have never had any trouble starting the tractor with the 6 volt battery that came with the tractor that I bought. I would not think a 6 volt would start a 12 volt system? The tractor has a coil and volt reg.

Any help determining what system I have would be great 6 volt or 12 volt. Could something of been switched to make it work with a 6 volt battery? I need to replace the wiring harness, so I need to tell the dealer which one to order, 6 volt or 12 volt?

That tractor was originally equipped with a 12 volt system. Does the identification tag on the generator have a red background? Generator number
1100401? Those indicate 12 volts, negative ground. After any significant change to a charging system with generator, be sure to connect the battery correctly, then polarize the generator before cranking the engine.

I agree with Bus driver. If the regulator was changed to a 6v, putting a 12v battery in it and expecting it to charge will not work. If it tries to work it could let the smoke out of the VR. They usually indicate the voltage on the underside. JimN

Yes, the generator has the red tag and it states 12 volts. The current 6 volt battery is connected neg to ground. I would not think a 6 volt battery would start a tractor that was supposed to have a 12 volt system?

The Cub engine cranks pretty quickly with the original 12-volt system. I never tried a 6-volt battery with a 12-volt starter, but it seems unlikely to work. Maybe somebody put a 6-volt starter on an otherwise 12-volt system. The 6-volt starter is 1109603 or 1109611 black tag, cylindrical with the starting switch directly mounted. The 12-volt starter is 1107327 or 1109352 red tag, larger diameter at fields than at the commutator. It has a terminal stud for the heavy wire and remotely located switch.

A 6-volt starter could have been changed to work with a remote switch.

It also seems unlikely that you have a working charging system as a 12-volt charging system would boil the battery dry. Maybe it has a 6-volt regulator or maybe you typically run the engine too slow to charge much. Just a potential situation to check out.

Where is your starter switch? It should be in the dash panel. Presuming most of the original components are still there (likely if the original generator is still there) I'd get the correct 12-volt harness regardless of what operating voltage you go with, as it will match up with the other components. Looks like the original harness was 387262R91. Book shows replacement number 404353R1 although R1 seems odd for a harness.