This diagram is all you need to make it work. Get a 20 amp 4 pin relay from a parts store, normally used to operate things like fog lights or other high amp accessories.There are a lot of threads about voltmeters that read incorrectly or batteries that are being overcharged by the regulator. There is a common denominator and a fix.
The voltmeter isn't connected to the battery, it's connected to the electrical system. System and battery values are different due to connections and line loss. The older the bike, the more prone it is to have a wider variance between system and battery. Some as much as 1.5 volts. It's okay if you're smart enough to add 1.5 volts to the voltmeter reading, but there is downside. It causes the regulator to overcharge the battery.
The regulator sees the same voltage as the meter. 1.5 volts less than actual battery voltage. So it kicks the voltage from a nominal 14.x to 15 volts or better. And that's too high. Most charging systems are regulated to 14.2-14.4.
Here's the fix.
Break the ignition wire to the regulator, use it to close a relay that provides power from the battery to the regulator. Now the regulator sees actual battery voltage and regulates correctly. The nice thing is, you've also provided a tap so the voltmeter reads the actual battery voltage as well.
The regulator getting hot is normal. The only way to cool it down is to use more of the available wattage.dave0430, dave if the rectifier was getting hot can it cause it to over charge? regards walkabout