SOLVED loop frame generator trouble - not generating

[lazlokovacs]

Symptoms in order of appearance

-starting to get lower MPG

-engine cutting out momentarily at high RPMS eg 5k+, this got progressively worse.

-dash lights gently pulsing while on a run at steady speed.

-alternator warning light beginning to glow gently

-headlight glowing alternately brighter and then weaker

-alternator warning light turning on completely while bike running!!!

-luckily was near a friends house so have pulled over for the night.

I have a spare generator belt, the one on there looks pretty worn, thogh the generator IS spinning. I could change it???

Or should I be looking at the generator itself? Or the voltage regulator? which tests?

I have tools with me.

Thanks as ever.

[Kiwi_Roy]

Is your loop wired as original, this would be typical. I assume you have a generator with comutator.
http://www.thisoldtractor.com/guzzi007/schematics/1969_V750_Euro.gif

Your lights would be pulsing as the generator stopped and started generating

One thing you could check is if the brushes still have spring tension, if the brushes are too short they won't make contact, you could pack them up with a small piece of wood or something as a temporary measure.
Any arcing at the brushes, another sign of them being too short, take the cover off, you can run without that.

Are the bearings good, I found the armature on mine had touched the fields and torn a couple of the wires off. For some reason the armature was turning inside the NDE bearing, wore the shaft down.

Check all the wires including the regulator ground.

The generator light will come on if the Voltage to the field is not exceeded by the Armature Voltage
(in other words the field is On but the Armature is not generating)
It could be the belt, you could try changing it. 
There are different types of regulator, mechanical or electronic

[lazlokovacs]

cheers roy,

loop is wired as original, except greg benders headlight relays

using the standard mechanical regulator

[Kiwi_Roy]

The generator should generate with just the two wires to the regulator and ground.
Just check those 3 wires and of course the one from Reg to battery.
While you have the belt off if you push in the cutout the generator should operate as a motor.

It could be something wrong inside like field shorted to chassis or open
If you apply 12 Volts to the armature and Voltage to the field it should motor.
I'm not 100% sure if the field terminal needs to be touched to positive or negative (internal connection) if I get a chance tonight I will verify.

[lazlokovacs]

thanks for the great advice

I'm following everything except

'The generator light will come on if the Voltage to the field is not exceeded by the Armature Voltage
(in other words the field is On but the Armature is not generating)'

could you break that down even simpler for me????

[Kiwi_Roy]

Sorry, that was a bit confusing.
One side of the generator lamp has +12 Volts on it
Normally so does the generator so there is no Volts across the lamp.

If the generator armature is putting out less than 12 Volts there is a difference across the lamp so it turns on.

I'm almost certain that one end of the field winding is connected to the positive brush, the other end is grounded by the regulator,
Yes that's correct, Here's Greg Bender's troubleshooting pdf

http://www.thisoldtractor.com/moto_guzzi_loopframe_generator_repair_-_bosch.html

If you lift a brush off the armature the field should be open circuit to chassis
The field shorting to ground is a very common fault with generators, you can see Greg has re-taped his, plastic tape is no good for that.

[lazlokovacs]

great thanks

makes total sense

[Antietam Classic Cycle]

The first two symptoms don't say "charging system issue" to me.

I'd pull the generator (and regulator too), take them to an auto electric repair shop and have them tested.

[Kiwi_Roy]

I agree with Charlie, take the schematic as well.
That is if it's not just the belt, any auto electrician should be capable of fixing one of these simple systems.

Perhaps let us know where you are, might be someone with a generator they can loan you.

[guzzisteve]

Sounds normal to me, my lite comes on at idle. Maybe it's your battery.

[Kiwi_Roy]

I very much doubt its the regulator but just in case here's a brochure on Bosch electronic replacements
Looking at page 3 I think one of the first 2 would be appropriate.

http://www.bosch-classic.com/media/bosch_classic/teile_1/nachfertigungen/motor_2/generator_regler/Mini-Katalog_Generatorregler.pdf

[lazlokovacs]

Sounds normal to me, my lite comes on at idle. Maybe it's your battery.

my light is on when I'm at full revs with the bike running but thanks for your input

[Antietam Classic Cycle]

I very much doubt its the regulator but just in case here's a brochure on Bosch electronic replacements
Looking at page 3 I think one of the first 2 would be appropriate.

http://www.bosch-classic.com/media/bosch_classic/teile_1/nachfertigungen/motor_2/generator_regler/Mini-Katalog_Generatorregler.pdf

This is the only one I use with a Bosch generator:
http://www.thisoldtractor.com/moto_guzzi_loopframe_voltage_regulator_cross-references_-_bosch_electronic.html

and this is the one I use with a Marelli:
http://www.thisoldtractor.com/moto_guzzi_loopframe_voltage_regulator_cross-references_-_magneti_marelli_mechanical.html

[Kiwi_Roy]

I'm certainly not going to argue with Charlie.

[bmc5733946]

Electricity is never free, generators and alternators take horsepower to generate electricity, some up to 15hp. If the belt is any way questionable, I would replace it and see what happens first.

Brian

[Furbo]

+1 on what Charlie said about the regulator replacement. I'd start with checking grounds and then move to the regulator. The generator itself is pretty tough as long as the brushes a re good.

Should you need it repaired, look for a good Air Cooled VW shop as the bosch generators are very similar and there aren't many wrenches around these days who can actually 'fix' a generator.

[lazlokovacs]

SOLVED

top bolt holding the tool box was sheared in two

ground for the regulator is achieved by a wire coupled with said bolt

hence intermittent and then no charging

have duly re-routed the wire and re-tightened, loc-tited etc the tool box and all is as before.

thanks for all the input

[Chuck in Indiana]

Thanks for the conclusion.