MF TO 20 WILL START GREAT, DIES AFTER 5 MIN.

Your 8V battery was a temporary fix by the prev. owner to get the tractor sold, it likely won't give you long term satisfaction. Your 6V generator only puts out ~7 volts. My guess is you will need to charge your 8V battery regularly with a charger to keep a good charge on it. Your 6V coil may also be running hot and shorting out internally due to the 8V, then it may work fine when it cools back down again. I have seen 6V coils run for quite a while on 8 volts, but there were not designed for that long term. You would be better served by getting a 6V battery and fix'in up your 6V system to make sure it is charging and easy starting. Dirty connections are the #1 cause for poor charging, poor starting, & poor spark. 6 Volt systems don't work well with anything but clean, shiny connections on both the hot (negative), and ground (positive) connections. Oh yeah, make sure your battery is hooked-up right, should be positive ground unless your running an alternator and 12V system.
Troubleshooting the charging system is pretty easy once you get your TO running. If you need help with that, get back with us.

George

Recharge your battery first. Then start by checking out the ignition system. Pull the center wire out of the distributor cap, hold it near a good ground, turn on the key and try a start. You should have a FAT, BLUISH-WHITE SPARK. If you don't have a spark, it yellowish or orangy or even blue, you have problem with your primary ignition system. If you have access to an analog voltmeter you can make some simple diagnostic checks. With the key on and AND THE POINTS CLOSED, you should have battery voltage to both sides of the key switch and to the battery side of the coil. The small wire from the coil to the distributor should be conected to the coil terminal with the same sign as your battery ground and should read near zero. If you find anything other than this then check the component just upstream of where you got a bad reading. Also check to make sure that your points are clean, not pitted, corroded, or burned. Make sure they are set properly. Your problem could be caused by a bad key switch, bad connections, shorted wires, damaged wires, bad coil, etc.
If the ignition checks out, make sure that you have adequate fuel to the carburetor. There is a big plug in the bottom of the carb. Open the tank valve, get a container to catch the expensive gas and remove the plug. The fuel should CONTINUOUSLY gush out like a cow peein' on a flat rock for a good minute. If it dribbles or is intermittent, you have a restricted fuel supply. Look for a clogged filter starting at the carb fuel inlet elbow where the "secret filter" resides, kinked fuel line, clogged filter in the sediment bowl/tank valve asembly, plugged vent in the fuel cap, etc. rap the side of the carb with a wooden block. Sometimes the float hangs up.

If you don't find the problem there, then you may have to remove the carb. Sometimes the fuel boal fills with sediments from a dirty fuel tank and the float won't drop.

Do there checks in the order I have described and write down the results so you remember exactly what you found. If you find something that needs changing, change it and retest to look for the Holy Grail of the Spark Ignition System - THE FAT, BLUISH-WHITE SPARK!

This question is asked and answered on some YT mag forum at least twice a week so I'm not going to go into all those details. Search for "starts dies" and you should turn up bocoup details of things to test and how to test them.

Gerald J.