1988 yamaha moto-4 battery issues

[Louis Angel]

Anyone have a clue as to why my old 1988 Yamaha Moto-4 250
keeps frying the batteries?
4 years ago: Installed new battery. 1 week later, fried. THOUGHT battery was
bad, under warranty swapped for another battery. About a week later, FRIED!
Too embarrassed to try to get a third battery, ordered a third battery from O'Reilly's STILL thinking the other battery's from Interstate were just JUNK.
NOPE! 3rd battery fried like all the rest.
I am sure the carb is gummy BAD by now. :-/
Knee jerk reaction now is voltage regulator is bad. Have to go drag it out of the barn and get it up to my house and see what the actual voltage is when it is running. Will be a few days before I can get that done as when not flipping houses or farming I am also a small engine mechanic ( certified through Kohler ) and I paint houses too. So , , , , yeah, , , I can be quite busy now that I have retired. hahahahaha! Love to you all --- ride safe!!!