I found that with this same issue that the fix was to slightly bend the tip of the ball that
the rod attaches to that goes to the throttle at the carb, back towards the slanted floor board.
Keep in mind that in a 12 volt system the 12 volts from the battery (or more like 14 volts ) is only used to operate the starter and then when you release the key a ballast resister reduces the voltage to 8 volts to be used for running. So by using a 12 volt coil without a resister in a 6 volt...