Ok well after 4.5 grand rpm the voltmeter on the dash goes past 18 and battery light come on. So I figured, time for a new voltage regulator after 13 years. So I replaced it yesterday and inspected the brushes, still good. And I started it and voltage on the dash was reading better now. I was like ok kewl problem fixed. I reved it and sure enough after 4.5 grand rpm it did it again. Any suggestions? Could the rectifier cause this?