MM ZB 6 or 12 volt? I'm confused.

Just bought a MM ZB tractor from a gentleman here in New York. Before picking it up, I looked up specs that stated it uses a 6 volt system with positive ground. Put the 6 volt new battery in- no spark. Contacted him. He said it started it on a 12 volt negative ground. So I put the 12 volt in and she started immediately. Please note- there is no alternator upgrade-still uses a generator. Everything looks as a 6 volt should. There is no resistor in the line either. New amp gauge doesn't move after starting it. Excuse my lack of electrical knowledge that's why I ask for help. And a big thank you to my responders.

Don't know where you looked up your specs but they are wrong. A ZB is 12 volt, positive ground with a generator and voltage regulator. That is what my operators manual says and that is what my ZB is.

Yes, ZB is a 12 volt system, positive ground. The ZA is a 6 volt system. Basically the same tractor, just different clutch and platform.

I looked up specs that stated it uses a 6 volt system with positive ground. As others have said, that is for the earlier ZA and ZT series. The ZB came from factory 12 volt, positive ground. The previous owner may have reconfigured it for negative ground, which if properly done will work equally well.

Check your voltage regulator. Some are marked for positive ground, some for negative ground, and some for either. They can work for either polarity but should last longer if configured as indicated.

The battery doesnt care if it is charged by generator or alternator. Due to poor quality of modern replacement generator regulators, the alternator is more reliable and has higher output to maintain lights and other 12 volt accessories.

With positive ground, the + post on coil goes to side of distributor, with negative ground post goes to side of distributor.

With switch and/or lights on, engine not running the ammeter should show negative. If it shows positive reverse ammeter connections. Starter will turn same way either polarity

There is very little visible difference between the 6 and 12 volt systems with generator . The 6 volt battery would have 3 caps, the 12 volt 6 caps. On some, the 6 volt starters and generators had a black tag, the 12 volt had a red tag.

There is no resistor in the line either. The original 12 volt system used a direct 12 volt no resistor required coil so there was no resistor in the original system.

Amp gauge should show positive for a short time after starting and then drop back to near zero as battery recharges. Turn lights on with engine running, if ammeter goes negative you have a charging problem.