Just had a further dark thought.Having run the bike for a total of about 15 miutes without wiring up the dynamo etc. Have I cooked it? Hence low output, it was rebuilt.

Hi Pat.

If it was an alternator, it might cook,
But an unwired dynamo gives no output, cause the field get no voltage,
So unless it was hooked INSDE the dynamo in a way that both Field wires are hooked with the D, (Brushes)
All should be well.

If it was rebuilt, you may have a problem with the regulator, the field or brushes spring tention.
Does the brushes move freely in its path?
You can test the field by measuring it’s resistance.

Good luck,
Noam.

email (option): noam10@gmail.com

Hi Pat..6V at around idling speeds rising to 10 volts at say 1000rpm is normal output. The dynamo is regulated to below 10 volts during normal operation...Ian

email (option): ian@wright52.plus.com

Rode the bike 10 miles with all lights on. Still bright,and horn sounds the same.Turning on lights drops ammeter to -7 amps from centre point.When running this rises to -4 amps. With lights off it reads +1.5 amps.Any chance it's the ammeter?
Cheers Pat

What wattage is your headlight globe?

I am using a 6V 35/45W std bulb. I removed and tested the ammeter,using the headlamp bulb and it works ok in both directions.Running the bike gives 1.5/2 amps charge, but turning on the lights shows 4 to 5 amps discharge, revving up is slightly less but still discharge.
Any guesses? Cheers Pat

45w ??? I'd want an RM23 alternator before I'd go that high !

Standard lamp wattage is 24w.

There are halogens available and they give a useful improvement, especially with a re-silvered reflector.

I do my daytime running on a 10w halogen pilot bulb and haven't been tugged over yet.

That said, I suspect that the CZ27 ammeter is a general guide rather than a precision measuring instrument.

Total output on the short dynamo is 45 watts, 60 on the long one. That's per spec, which means that if your dynamo is not like-new (and, perhaps, your regulator is not exactly adjusted) you'll be getting less output into the system. With the headlight you are using there is really no way to avoid a negative reading. The 4 amps discharge you are experiencing means that the battery must make up 24 watts beyond what the system is getting from the dynamo. Then, when you turn off the lights you get a charge reading because the dynamo is now charging the battery which was partially discharged when the lights were on.

The difference between 35 watts and 24 watts, i.e., 11 watts, at 6 volts, means almost 2 amps deficit just for the headlamp. The difference between your high beam and a 24 watt lamp is 3½ amps. Add the taillight and there's your problem. (I specify "at 6 volts" because at full tilt the dynamo should be putting out closer to 7 volts.)

I guess that's the long way of saying, it sounds like the problem is probably not your dynamo but other parts of your system, which must be brought up to snuff before the ammeter reading becomes a meaningful indicator of the dynamo's function.

email (option): jonny.rudge@verizon.net