Obie.........you complain......."So anyway, I ordered a 12 volt system and installed it. Tractor starts fine, it charges, runs for a couple minutes and then cuts out"........couple minutes of runtime is almost always a BAD condenser. Condensers can be BAD right outta the box. Most are good fer at least 100-volts but the way they are manufactured can be BAD rite outta the box. Do I haffta tell you to chance yer condenser??? You doubt??? Re-install yer OLD condenser.
Recommend using a real 12-volt coil, NAPA IC-14, uses NO resistor ever. And is even has HOTTER sparkies ........Dell, yer self-appointed sparkie-meister