Mechanical Regulator Adjustment

[PHeller]

The voltage on my 78 isn't where I'd like it to be at lower rpms.

It's charging 12volt at 2000rpms, but that's not enough to charge the battery and run my headlight.

I know I can adjust a few things on the mechanical regulator to up my voltage.

Inside Points: The points closest to the bike, which the actuator DOES NOT rest on most of the time.

Outside Points: The set of points to the outside of the bike, where the actuator appears to rest most of the time.

Spring tension: the screw closest to the resistor that appears to control tension of the actuator.

How do I adjust these to get 14volts?

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[retiredgentleman]

This is a diagram that was posted by 5twins...................available in manuals.


My advice................buy a VR-115 solid state automotive regulator for less tha $20.00. No fiddling, no adjusting, just install and forget about it.

 

[5twins]

All I adjusted was the points gap #4, it was out of spec (too big). That's all it took to put the charge rate back where it belonged.

 

[xjwmx]

A bunch of us were forced to become experts on mechanical regulators last month.

 

[pamcopete]

1. Adjusting the mechanical regulator is very much a trial and error experience, with the emphasis on error.

2. After making your initial adjustment, you will find that the voltage changes when you replace the cover because the cover is steel and it influences the magnetism of the relay, so you have to make another adjustment, replace the cover, check the voltage etc. etc.

3. Then, you have to check the voltage under various load / no load conditions, like, with the headlight on and off and the battery fully charged and right after starting.

4. Then, you have to check the voltage at high RPM, like, above 4,000 or equivalent highway cruise speed because the alternator is capable of producing more amps at high RPM's so therefore the field current, which is what the "regulator" is regulating, becomes very sensitive to change.

5. Then you have to check the voltage at various temperatures because the resistor in the regulator changes its value when it gets hot.

6. Also, the regulator will produce a different output depending on the condition of the slip rings, so you have to clean the slip rings often to maintain any consistency.

7. Also, the relay and the resistor in the regulator draws quit a bit of current, which deprives the rest of the electrical system of a few amps.

8. While doing these adjustments, you will have to start and stop the engine about 100 times and wait each time for the battery to recover before checking the voltage. The engine will overheat and boil the oil, necessitating a complete engine overhaul...

So, like RG says.....here are the steps to a happy and trouble free regulator life:

1. Carefully remove the 35 year old mechanical regulator.
2. Sell it on Ebay to someone who has not read this.
3. Use the proceeds of #2 to buy a new solid state regulator with a one year warranty for $20 or less.
4. Install the solid state regulator and observe a perfect 14.5 Volt reading...
5. Use the money left over from #2 and #3 to buy a six pack of your favorite brew..
6. Ride. Enjoy. Life is simple...

 

[PHeller]

I wonder if my coil isn't messed up...I know my rotor is good, my brushes are good, but the fact that I'm making low charge at idle seems less common than high charge with a faulty regulator.

I guess the better question would be, is it common to make 12 volts at 2000rpm?

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[5twins]

2000 really isn't an RPM that we check charging at. Full charging should occur by about 3000-3500 RPM so you should be checking it there. 12 is low even at idle (1200). Does your charge rate change at all when you rev the bike? You should see about a 1 volt change between idle and 3K. If the charging rate doesn't increase at all, you have a charging problem that a voltage regulator adjustment probably won't fix.

Mine was putting out about 12.5 at idle, 13.5 revved, before I made the adjustment. Adequate but not ideal. Adjusting the #4 gap to spec gave me 13.5 and 14.5, cover off. Installing the cover dropped that to about 13 and 14. I decided to try that for a while and see what difference it makes, if any.

 

[PHeller]

Yea it does increase to the 13 volts or so by 3000, I think.

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[5twins]

OK, then you may benefit from a regulator adjustment. My core gap (#1) was OK but my points gap (#4) was too big @ about .020". I closed it up to the spec of about .015" or .016" and that did the trick. I didn't need to fool with the adjuster screw (#10).

 

[retiredgentleman]

PHeller;

You have to start with a fully charged battery when checking charging/regulator operation.

Fully charged means battery = 12.5 volts

Start engine,wait a few minutes................battery should be at 13.5 volts at 1200 rpm

Rev engine to 3000 to 3500................battery should be 14.2 to 14.5 volts

How old is your battery?

If the electrical load is too large, then the charging system will have trouble dealing with it
i.e. make sure your high beam is off, make sure you have no extra loads such as driving lights, no heated grips or heated seats allowed( I guess not if you are in the southern US)

 

[PHeller]

I ended up charging the battery to a solid 12.5 volts and now at 2000 rpm the bike is charging at 13 volts, so thats an improvement.

The main reason I don't want to spend any money on this charging system is that I've got 75% of the parts for a PMA swap, just waiting for my first paycheck of my new job.

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