Wildguzzi.com
General Category => General Discussion => Topic started by: Groover on May 20, 2024, 07:15:42 AM
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Hello, need some help - My G5 has been having intermittent charging issues, finally thought I had solved the issue with a new regulator - last night, the dash lights, head light and turn signals went out pretty quickly while riding, then by the time I realized that, the engine started to misfire then within less than a minute of all that, the bike just backfired and died. Dead battery, but also killed the engine electrics - where should I look? Is that a rotor issues?
Please advise - short week, didn't want to be bike stranded! This is on my 1981 G5, all OEM circuitry and OEM style parts.
Thank you in advance for the help.
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Ignition switch corrosion is my first place to look. Checking voltage can be misleading. You can get a voltage reading, but due to massive corrosion in the ignition switch, you are not getting any amperage current. I chased multiple problems on my Quota rebuild. When i pulled the ignition switch apart and cleaned the green out of it, the bike ran better and the lights were brighter.
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Thank you John, will check that a little later, though I did just replace that earlier this year. The symptoms of that were a little different, that, when it acted up it was basically a crisp on-off, this was just an abrupt horrible performance (I was at a stop light) acted a bit as if were going into reserve (not the case) I upped the throttle to keep it running, and just got worst until it just backfired and died - dash was also very dim, almost out but not all out, turn signals did not work either during that time which was a total of maybe 1-2 minutes.
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I chased a charging problem for a long time and it turned out to be a hairline crack in the brush holder, the brush weren't getting good contact to the rotor. And a few years later there was the twisted rotor problem, basically the claws on the rotor twisted:
https://wildguzzi.com/forum/index.php?topic=102768.90
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mangled brushes and/or rotors would cause engine running issues, correct?
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Unplug all of the Molex connectors from the back of the headlight, clean with Caig DeoxIT and plug back in. Might not help, can't hurt.
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Will take a look at that as well, did that a month or so ago as it had unplugged, cleaned and snapped it back in, may have come loose again. Not sure - what are the symptoms (to the engine) when a rotor or brushes go bad?
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Will take a look at that as well, did that a month or so ago as it had unplugged, cleaned and snapped it back in, may have come loose again. Not sure - what are the symptoms (to the engine) when a rotor or brushes go bad?
I zip tie the Molex connectors together to avoid that problem. There are no motor symptoms when either the rotor or brushes are bad.
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Check the wiring under the fender to the tail light. It sometimes shorts out because of its living conditions. I’d suspect the rotor as well, they can develop a flying short when the centrifugal force makes it short out when running.
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Thanks again for the replies, Went home, bike started right up (vs dead when I parked it) dash lights worked and so did the turn signals, so that doesn't help. I took the rotor cover off (just our of curiosity, thank you for clarifying John A), all looked good, checked the Molex connectors at the headlight, all was snapped in and tight, disconnected and reconnected them still and all was nicely lubed from a few months ago (with ACF-50), switch is new so hoping it's good, seems to be, I did tug on the cable to the taillight and turn signals in the back, nothing visible that looked like could short-out, but did move them a little from there current resting spots - will check more closely after work, but at a glance, all looks protected (no rubbed out wiring) - thanks again - need to build some trust with this beast again, got stranded, luckily just 1.2 miles from my house, wife with me, we pushed it slightly up-hill in the dark, so the word Vintage bike is a little taboo at the moment in my house :azn:
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Deferring to John's point about the switch, have you replaced the original switch? The reason I ask is because I'm always suspicious when a bike fixes itself with no input from something I did to the bike.
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I replaced the switch with a new one not too long ago (a few months maybe), maybe it failed, not sure - I'll definitely take a better look. I agree, not particularly at ease with it all of a sudden working...
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I can’t imagine it would fail so quickly but you might have a loose connection.
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Ordered a replacement switch just in case to have on hand with the holiday weekend coming up. I'll check everything thoroughly again, thanks again everyone for the help. At least I know now it's now the rotor, though still not totally confident on the charging issue - looking at these as two as different issues. I did replace the battery this year as well as the regulator - have not checked the diode board yet.
I can deal with the battery not charging, I bought a jump starter to carry with me when going out of town, the dying out while backfiring was new to me. Totally unexpected.
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Thanks again for the help, and hope everyone is have a safe Memorial Day weekend.
On this, the bikes seems to be running, no engine issues. I did go over all the connections, things looks really good. I spread and cleaned the molex ones at the headlight, all snaps in tightly. Checked the charge light bulb, it's not lighting up at idle (it has in the past), but the bulb and connectors are good.
At this stage, I have new battery, new rectifier (I do have a new ignition switch now on hand, but that would be for the running issue and I'm good on that I think), but for the charging, could the rectifier/diode board be the issue? I have a spare in my storage unit, will likely try it tomorrow.
Bike runs, rode it a few hours yesterday, though not charging. I have a NextPow jump starter strapped to the bikes rack, and will likely be using it by end of day, lol.
So next in line is the replacing the rectifier. What else it could be. Wiring is good
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stator
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Which should I try to replace first. I have that as well.l
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Just checked voltage, reads 18.01 volts after battery change over night on battery tender, which seems high, anyway, giving it throttle doesn't change the ready, so apparently not charging, but could that be because the regular is set to 14 (something) volts? It's one of the duralast (I think name of brand) anyway, just an update and had a meter on hand.,
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My CX100 had the same symptoms a few years ago,,, bike ran fine,,,but no charging,,,had to recharge the battery at home & ran it for quite a while as a total loss system.
Later discovered,that the sensor signal wire to the R/R, had become disconnected;,,, no signal,,no charge;,,, fixed by simply reconnecting the wire.
If as you say,the wiring & connections are good, maybe there is a diode or similar on the same path,burnt out inside the R/R.
Fwiw idk
Good luck
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Rotor. Did you check ring continuity?
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https://www.euromotoelectrics.com/default.asp
I thought these guys had a trouble shooting guide but I don’t see it now.
As you probly know the lite has to work for it to charge. Did you ohm the slip rings? Is there 12 v to the DF terminal on the stator?
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mangled brushes and/or rotors would cause engine running issues, correct?
Disconnected brushes or a failed rotor (on my T3) show no visible symptoms whatsoever. You just run until the battery is empty. Then you know. CHARGE failure light goes on through rotor and brush continuity. Loose that and you don't get the red light at key ON. AND you don't get a red light indicating you are discharging as you ride.
Wore a brush short and it hung on the pigtail wire in the holder. Dead Odyssey was the indicator. Thank goodness it failed top of a long hill.
Another time couldn't restart after fuel up. Overnight charge at a sympathetic neighbor's and I made it home on the same Odyssey's box of sparks. The rotor had gone OPEN circuit.
One time I did have a ground cable loosen up at the chassis and the intermittent symptoms were about to make me nuts. Finally spotted the loose connection and all was well.
Once a year I spin the fuses in their holders and spray them with ACF-50. Used to die while riding every two or so years. Spinning the fuse reestablished sufficient contact to continue the journey. Now the annual "oil and spin the fuses" is on the maintenance schedule.
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+1 on spinning the fuses to clean them , especially the VW type :thumb:
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Thanks again, update, just cleaned and ACF50'd the fuses, same. Will keep updating this post with the fix. Haven't had a chance to replace the other parts. Thanks again.
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https://guzzitek.org/gb/ma_us_uk/1000/1000SP_G5_Atelier(GB).pdf
Page 127 says how to test.
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These still have a diode board? Thats the first place I would look. Make sure all the spade lugs are tight and don’t have signs of overheating from poor connections.
Pete
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ACF50 would not be my choice for electrical connections. Caig DeoxIT would.
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ACF50 would not be my choice for electrical connections. Caig DeoxIT would.
DeoxIT is a cleaner as far as I can tell.
ACF-50 is a preservative and lubricant.
So DeoxIT to clean the stuff up.
Then ACF-50 to keep it from re-oxidizing and keep it lubricated.
Spray that stuff liberally into all handlebar switches and they work and last forever. Fill the connectors and they stay connected. FAA approved for all aircraft electronics as it will not damage any non metallic parts. Super penetrant. So it gets to all associated parts of the switches.
I put that s#it on everything!
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Did the test posted and quoted by ohiorider in this thread, and it's definitely the rotor. I'll be replacing that hopefully later today (weather dependent, no garage)
https://wildguzzi.com/forum/index.php?topic=78054.0 (https://wildguzzi.com/forum/index.php?topic=78054.0)
I'll follow up with the "for sure" once it's all set and done, but looks like the rotor is it.
Thanks again.
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Wild a$$ guessing..
Try measuring the rotor brushes…..release the spring and pull them out..lower limit is in the service book I believe
Mine wore down enough to not be close enough..
But they looked like they were fine
The wire hung up on the holder ..
and the brushes were the tiniest distance away from making contact ..they ‘looked and felt fine’
Describes your no red light condition w the key on
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Brush spring base can also be fitted 1/2 turn wrong in rotation and not supply sufficient pressure for consistent charging. Found that one out after reading brush pressure specs somewhere or other.
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Thanks again guys, ended up scoring and ordering a new Rotor (NOS Bosch Original) The spare I have doesn't look too good, so opted for a new replacement. The one that just failed only had about 11,000 miles on it, it was from one of the replacement kits I bought when I restored the bike.
I may replace the brushes and brushes holder with springs maybe, I don't think that was ever replaced. I did replace the brushes as part of the kit at that time.
Thanks again, I should have checked the rotor continuity to begin with and also as advised here. What got me was the battery dying and the bike ALSO dying out, which still doesn't make any sense.
For others and myself in the future - I have been chasing the battery charging issue for over a year now, been living with putting on the the charger when home. All has checked out, has been a truly frustrating and intermittent issue, and I think it may have been the rotor all along, which may have had a split in the wire winding that maybe was open at times maybe not open others, who knows.
What finally did it I think, which made the it go out for good was a nice stretch of highway at high speed, as this last all this happened off the exit ramp once I got into town.
Before this, all was looking good (would even get a charge voltage of 13V + and the light would come on at idle, seems it charged, but then there were those random days on occasion that the battery would be dead by the time I got home (daylight running headlight would run it down).
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[SNIP]
Thanks again, I should have checked the rotor continuity to begin with and also as advised here. What got me was the battery dying and the bike ALSO dying out, which still doesn't make any sense.
[SNIP]
If the battery dies and the alternator can not supply current there will be no source for sparks. The engine will stop.
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Most often when a rotor or DC armature goes a wire breaks where it goes into the slip ring or commutator. When you get your new rotor check the resistance between the slip rings and compare with the one you are replacing.
Pete
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Rotors seldom go past 50K miles if the electrical system hasn't been cleaned up, etc. It's the most common problem on the Bosch system.
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Just received this delicious NOS OEM Bosch Rotor - Reads 3.4 Ohms, the old one I was going to install reads 3.2 Ohms. The one currently installed is open circuit so it's a failed one for sure.
Has some sort of protective coating, it's not wax, it's almost like a really thinned out paint - should I leave it or remove it? If so, with what? Almost thinking I should keep this as an antique and put my 3.2 Ohm one it ;-)
(https://i.ibb.co/Y8R60bF/Bosch-OEM-Guzzi-BMW-Rotor.jpg) (https://ibb.co/Y8R60bF)
(https://i.ibb.co/wYgzg18/Bosch-OEM-Guzzi-BMW-Rotor-Front.jpg) (https://ibb.co/wYgzg18)
Thanks again :bow:
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Do not remove the shellac that coats rotor windings. It protects the wires.
I used to get my rotors from-----------http://www.motoelekt.com/
Made to meet aircraft standards. Never had one of his go bad.
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Wot Steve says. It helps keep the wire from moving around under centrifugal force
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I have a spray can of red shellac for armatures that I bought years ago. Make sure if the shellac is damaged you are not open and either spray or brush on more shellac and recheck after it dries. It insulates the winding which must be wound tight but not make electrical contact with each other. A Wikipedia quote that says it well. "The shellac locked the wire turns in place, provided extra insulation, prevented movement and vibration and reduced buzz and hum. In motors and generators it also helps transfer force generated by magnetic attraction and repulsion from the windings to the rotor or armature". Preventing vibration which may be a cause of failure would be a good reason to make sure the shellac is in good shape.
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On one of these Bosch systems, always check the continuity/resistance of the armature FIRST. 95% of the time that's the problem. If you really do have an OEM NEW OLD STOCK armature, (it doesn't look NOS to me, those didn't have all that shellac), pay attention where the two ends of the wire come and run to the comm rings. Like Pete says, that's the weak point. If I remember right, the old OEM ones didn't have holes, and the wire came up and over the frame thru a paper or fabric tube to insulate it before reaching the rings. Even more failure prone. In either instance, if that wire isn't shellacked down good, do it. Don't forget, if the wire is uninsulated, make sure it's not touching the frame when gluing it up. Once upon a road trip long ago, I had one fail. The wire broke, where I could get at it at least. Thanks to a solder gun at the gas station up North, from the friendly old timer running the place, and a magnum or so of JB Weld to glue it down, I made it the rest of the way. And I got another couple three thousand miles out of it.
TdF
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Thanks again, still haven't has a chance to install it. Looked at the listing where I got it, and it says New, Unused, and said Bosch, so assuming NOS, but who knows. Good link guzzisteve (http://www.motoelekt.com), will use that in the future. Thank you all for clarifying in the shellac, makes sense. Its the green part of the metal that I was wondering if I should remove, seems it can stay?
Posting a few more photos just to share.
(https://i.ibb.co/86m5csX/1.jpg) (https://ibb.co/86m5csX)
(https://i.ibb.co/DG6s1Wm/2.jpg) (https://ibb.co/DG6s1Wm)
(https://i.ibb.co/dckPk0D/3.jpg) (https://ibb.co/dckPk0D)
Thanks again.
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Maybe just the pictures, but those commutator rings look really rough. Almost like they are not finish machined.
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Finally replaced the rotor, worked like it should for 1 day, now the charge light is permanently on. Might be stator, yellow output is low
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New rotor. Polarize it.
TdF
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Check it across slip rings for ohm's or open(broke wire). Good Luck
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The slip rings look like they have shellac on them. They should be clean.
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Charge light is lit by the continuity of the exciter current passing through the brushes, slip rings and rotor coil. If the charge light is lit your brushes, slip rings and rotor coil are continuous.
This is assuming all your wiring is stock and there are no shorts.
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I cleaned the slip rings, they were just dull, the rotor has continuity, wiring is stock (Greg bender), it all worked perfectly for a full day. Parked later in the day, then when I started riding the light would stay on. I had parked and started tre bike throughout the day a few other times, and all was working. I checked the regulator with another I had, sane difference. I have a spare diode board I might try later. All looks good otherwise. Thanks again for the assistance.
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I had a similar problem on the CX, brush holder had a hairline crack and it was enough to cause a charging problem. At the time there was no way to buy a brush holder but they can now be purchased through MG Cycle. Worth a close look.
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You do have the brush springs wound about 3/4 turn when they are pressing on the brush. This puts about a 1 pound load on the brushes.
The brush springs installed 180° incorrectly will still push on the brushes but at a pressure insufficient to guarantee contact while the rotor is spinning and vibrating.
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Would someone be able to clarify what testa_di_formaggio mentions please? The polarizing, which I think is the same as what is mentioned here: https://wildguzzi.com/forum/index.php?topic=91322.0
I do have a spare 12v battery I could use for it if that makes it easier.
A bit at a loss with this, I ordered a good/used stator and rotor, will try that next. Again, all seems to be OK when I look around test what I have in there now, though I don't get the expected 40v between pairs of the 3-yellow wires when at/around 4K RPM (mentioned on the linked post), I got maybe 20volts between pairs), and 1 pair was less, so thinking the stator is faulty?
Last try at this, then I may just order a whole new kit. I had replaced them one already around 11,000 miles ago.
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Would someone be able to clarify what testa_di_formaggio mentions please? The polarizing, which I think is the same as what is mentioned here: https://wildguzzi.com/forum/index.php?topic=91322.0
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Testa di Formaggio himself, if have this nom de net correctly associated, polarized my own new rotor in front of my eyes. Worked as advertised. Try it. The battery in your bike will do.
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Ok, thank you Moto. I read the first part of that thread again, and makes sense I think. Basically + and - to each slip ring for ?? amount of time, thinking 30 seconds maybe (?) and that's it?
Edit: Isolated of course. (no brushed touching)
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Ok, thank you Moto. I read the first part of that thread again, and makes sense I think. Basically + and - to each slip ring for ?? amount of time, thinking 30 seconds maybe (?) and that's it?
Edit: Isolated of course. (no brushed touching)
Isolated. This was over 30 years ago. I think there are only two slip rings, right? Briefly press the positive wire to one and the negative to the other. Not more than about a second, I recall. Could do it longer if not successful at first. No need to repeat the other way around, or to worry about which ring gets the positive charge, I believe, since it is an alternator.
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Alternators don't have to be polarized. If wired correctly the alternator is fed a current through the charge light filament each time you turn the key on. That current is enough to generate a magnetic field in the rotor and start a current flow in the field.
It was generators that had to be polarized. From the factory they had no magnetism in the field. So a spinning armature did not generate electricity. Running the battery (once at install) through the field left residual magnetism in the field poles. This was enough to start the process of generation when the armature was spun up on subsequent starts.
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Alternators don't have to be polarized. If wired correctly the alternator is fed a current through the charge light filament each time you turn the key on. That current is enough to generate a magnetic field in the rotor and start a current flow in the field.
It was generators that had to be polarized. From the factory they had no magnetism in the field. So a spinning armature did not generate electricity. Running the battery (once at install) through the field left residual magnetism in the field poles. This was enough to start the process of generation when the armature was spun up on subsequent starts.
I agree with this reasoning. Nonetheless, the very knowledgeable TdF performed this simple operation on my T3 with immediate effect.
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I'm still curious if the OP has confirmed proper pressure on the brushes. It's easy to mismount the springs by 1/2 turn and not get proper contact on the slip rings.
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I checked the springs and brushes last week, and they looked good. I did not remove the springs nor the brushes when I pulled it off the front of the engine to replace the rotor, so all stayed in place in the housing in that regard. Everything worked correctly for 10,000-ish miles until this last rotor failure (which did have a broken wire), that is when the dash light went out prompting this thread. Last week or so, I finally got around to replacing the rotor (which is when I checked the springs), checked everything else while at it again. Once the rotor was replaced, the dash/battery light would only come on at low rpm. then off once it hit 2k-ish maybe (normal operation), also was charging (voltage would hit around 14v+ when giving it a little throttle), thought the problem was solved, until this last failure, which stopped the charging and also made the battery/dash light stay on consistently. When I check things now, seems the only issues that I can tell is the low output from the yellow wires. At this point, going to wait until this eBay stator replacement shows up, then I'll follow-up with an update.
Sorry for the slowness on this. I don't have a garage, then it's too hot, then it rains, when the weather is nice I opt to go for a ride; the trickle-charged-up battery gets me through the evening rides after work, so I've been able to 'get by' that way, and I also carry a small jump starter with me if it completely died out, which hasn't to this point, though I don't go too far
Thanks again for the help - I will hopefully and soon be able to get the final answer on this.
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Ron is correct. In theory, alternators don't need to be polarized. However, I've had to do it numerous times over the years, and recommended it to others having problems. Perhaps "exciting" is a better term. Usually, on installation of a new or re wound armature, or on bikes that have sat for a long time. I've figured it's related to residual magnetism, at least that's what I took away from the old instructor at Delco in Indiana when I was there for DC unit diagnosis and repair 30+ years ago. The busses I worked on had "generators", providing 12 and 24V DC. And then I realized that they were pretty much the same setup with the Bosch charging system on my T3. It's an alternator, producing AC, then rectifying it to DC ? Whatever, have forgotten the theories. None the less, our instructor told us we had to polarize the unit on install. His statement was kind of "you need to kick the ass of the electrons in the circuit so they know which way to flow". And low and behold, Dave R mentions it in Guzziology as well. And NOTE. You are not jumping the C rings. You "flash", meaning quickly touch and remove a jumper wire from your battery + to D+ (I think) on the stator. You'll see a spark, pull the wire off. You don't need (or want to I would think), to sit there holding the wire there for time eternal. Since I can't remember which terminal on the stator it is, if D+ doesn't do the trick, try it on the DF terminal, same deal, quick touch of the wire. I've never hurt anything doing both. That or look it up in Guzziology, trust me, it's there.
TdF
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The older Bosch generator as used on the BMW /2 series was a generator that produced direct current. The rotor consisted of a series of coils that were connected to a segmented commutator. The brushes picked up the current at the same point in the rotation cycle. Hence they got DC directly from the device.
(https://i.ibb.co/99VpZM2/s-l1600.webp) (https://ibb.co/99VpZM2)
These had to be polarized at install (or after years out of service). It was something about dropping a hot line in an external stator terminal on the fully assembled unit for a half second or less. Been about 20 years since I had to polarize the /2.
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Stator. Received the used parts today, and all works. Charges at 14.4v.
Old stator has discrepancy between the 3 leads. 1 combination read .7 ohms, 1 read .8 ohms, and 1 read 1 ohm. The "new" reads .8 between all combinations.
I never did flash the rotor as suggested (was going to be a next step.
This thread basically covered 3 issues, which still leaves it a mystery to me why the bike stalled and battery was completely dead when the rotor failed.
Synopsis: ran the bike hard on highway, on exit ramp at first light, bike stalled, dash lights all out (probably completely shorted or dead battery), next day, bike started, charging light out and not charging, replaced rotor, bike worked for almost a full riding day, stopped to get something to eat, battery charge light stayed on, no longer charging. Replaced stator, and all good now.
Thank you all the help and trouble-shooting along. I hope this helps someone in the future.
Side note, the used parts came with an other rotor (which I did not use) looked to be rewound, ohms on that were 4.4, mine and I believe typical read 3.3-ish. - what would a higher resistance rotor yield? I don't plan on using it, just curious.
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Congratulations, always a good feeling when you finally solve a mystery charging problem.
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When the rotor fails, there isn’t any additional needed volts added to your battery to replace what you’re using running down the road…..keeping it about at least 12.3-12.4 at rest..
no water flowing across the water wheel so to speak
All your electric usage (coils, lights, turn signals, radar, cb radio, coffee maker) while running starts to slowly deplete the battery lower and lower until boop! Your battery is below a usable limit and you have become an electrician on the side of the road….
There is a solution Ive heard, of making your way home by stopping at Walmert and replacing the newly purchased battery every stop…. :bike-037:
Glad you found the problem…next is a diode board…add another ground there to the transmission
Then a voltage regulator..adjustab le
Then the yellow 3 wire harness…
Then the brushes..
I can’t really complain about the system when Ive never ridden any other bikes that far…
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Time for an update, the saga somewhat continues - battery charges, but barely.
Symptoms:
Engine, Cold - Dash light Red for maybe a mile or so, will stay that way until I rev it up to say 4k+ rpm once, then it operates normally after that - still would prefer it to go off a little sooner, but I think that is the regulator, so I plan on swapping that with the older one as I think it made the light go off at a lower RPM in general - both the old and the new one are the EnDuraLast adjustable version - I could try to adjust it, but I can't get to it so I might as well put the old one back on once I take the tank off as it seemed to work better for my riding style and location (mostly stop and go) https://www.euromotoelectrics.com/product-p/vr-extadj.htm (https://www.euromotoelectrics.com/product-p/vr-extadj.htm)
I never did replace the diode board, but I also have an old good one (I think, tested OK) one on hand if needed. All connections are clean.
All seems to work, but that first part where I need to ride it a bit, then sort of make it kick in with a burst of throttle is weird - what would that be? What's really odd and what got me is that I rode it the other day quite a bit, never did give it the 'burst rev" for the dash light to go off (and start this odd charging cycle), and it killed the battery. Luckily I had the jump starter that I've been carrying around, got it started, then rode it a little harder, battery charged, back in business.
The behavior is pretty consistent so now I know how to work it reliably so to speak, but what would cause the delayed start on the charging system? Is that a symptom of a failing rectifier?
Wanted to also add that when I start it from say sitting overnight, I can rev it till the engine blows and it never makes the light go out and start the charging, seems the engine (or diode board? or Rectifier?) need to heat up a bit first before working.
I like to fix things the hard way and drag them on forever as you can see, plus, figured those involved in this were waiting for a new episode anyway :-)
Thoughts on symptoms of a failing diode board?
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My "idiot" Light goes out at 2,000 RPM and is pretty much out unless I get stopped around 700 RPM.
Did you confirm that each brush spring is wound 3/4 turn from relaxed when seated on the brush and each brush is moving freely in its holder and there is no binding at the pigtail wire.
The brush spring can be installed in two positions 180° different. The system will function with either installation. It will be unreliable with 1/4 turn preload on the spring. It needs 3/4 turn on the spring.
Just pull the front cover and lift the spring off the front brush. Let it relax foreward of the holder and be sure it is 3/4 turn beyond "working" position. (Then assume the rear spring is the same). If you only get 1/4 turn to relaxed pull the spring and rotate it 180° to correct placement.
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Thanks again, will try that this weekend. I never checked on the replacement stator when I got it.
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Try a new diode board,is the one in there the original?
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Throwing parts at a charging issue, and hoping something will stick, is using a shotgun to kill an ant. You will miss. The function of the various components is quantifiable, a volt/ohm meter is your friend. Find the issue. Measure twice, cut once. Also, there are parts changers are then there are mechanics. Grounds, grounds, grounds.
TF
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Many of the old alternators relied on the current through the charge light to provide the initial rotor magnetism, if the bulb was burnt out they might not start to charge.
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Just wanted to follow-up on this, has been a while. All checked out OK with the springs, and all seems to be working normally it seems. Still would like the charging to be stronger, so I may upgrade the Alternator to something better some day - as far as the issue goes, best I can think of is that the old brushes needed to settle in with the new rotor - not sure, but all seems to be working now and it was a gradual improvement.
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Stator. Received the used parts today, and all works. Charges at 14.4v.
Old stator has discrepancy between the 3 leads. 1 combination read .7 ohms, 1 read .8 ohms, and 1 read 1 ohm. The "new" reads .8 between all combinations.
I never did flash the rotor as suggested (was going to be a next step.
This thread basically covered 3 issues, which still leaves it a mystery to me why the bike stalled and battery was completely dead when the rotor failed.
Synopsis: ran the bike hard on highway, on exit ramp at first light, bike stalled, dash lights all out (probably completely shorted or dead battery), next day, bike started, charging light out and not charging, replaced rotor, bike worked for almost a full riding day, stopped to get something to eat, battery charge light stayed on, no longer charging. Replaced stator, and all good now.
Thank you all the help and trouble-shooting along. I hope this helps someone in the future.
Side note, the used parts came with an other rotor (which I did not use) looked to be rewound, ohms on that were 4.4, mine and I believe typical read 3.3-ish. - what would a higher resistance rotor yield? I don't plan on using it, just curious.
Glad you are all sorted. This was a good thread and troubleshooting for others in the future.
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I looked for a 81 G5 on greg Benders Thisoldtractor site
All I could find was this 1978G5 showing a typical Bosh alternator
https://www.thisoldtractor.com/guzzi007/schematics/1978_G5.gif
These alternators rely on the alternator dash light to excite the alternator
they also have a miserable set of fuses which lose contact over the years.
Pull esch fuse and rub the contacts at each end on your jeans to polish them up
bend the spring clips to create more tension and smear the contacts with Vaseline so they don't corrode
Take the cover off the fuse box and measure for Voltage at the fuse terminals, it should read 12 Volts in relation to the chassis
Some of the fuses will require the key to be in On position
1978 or 1981 this bike is getting a bit old in the tooth, Guzzi Electrics was never the best.
Motto Guzzi, making Electricians out of riders since 1921