Topic: CB550 No Charging

[titan joe]

I've been following TwoTired's charging system diagnosis procedure. Here's a copy of it

Charging system methodical verification checks, CB750, CB550, CB500, CB400, and CB350.

Begin with problem verification and characterization with recorded data.
A -- Fully charge a known good battery.  Let it rest for 2 hours, off the charger, and measure the battery voltage.  (Target is 12.6-12.8V.)
B -- Start the bike and measure the battery voltage at idle, 2000, 3000, 4000, and 5000 rpm.
C -- Repeat the measurements of B with lighting off.

The above tests identify charging system success, failure, or degree of "faulty".  The success voltages are listed in the Shop manual.

D -- Assuming the above indicates faulty, do check the RECTIFIER diodes with a diode tester or ohmmeter capable of testing diodes and uses more than .7 volts to make the test(s).
Of the twelve tests made in D, six must read low ohms and six must read very high ohms.

E- assuming no faults were found in D,  Measure the white and green wires disconnected from the REGULATOR.  CB750s should 6.8 ohms - ish,  CB550s/350s/ and 400s should read 4.9 ohms- ish.

F- If there are no bullet holes or road rash/divots on the alternator case, the stator is probably good.  But, you can check for yellow to yellow continuity (.35 ohms) among all the wires, and that no yellow wire has continuity to the engine case.

G- Assuming no faults found in D, E, and F, measure the disconnected terminals of the REGULATOR.  The black and white terminals should measure zero ohms (subtract meter error if there is any).  Higher than Zero ohms, indicates internal contact contamination needing cleaning and attention per shop manual.

H - Assuming D, E, F, and G have not found faults. We can verify all the of the charging system minus the regulator is functioning correctly, by using a temporary jumper to connect the disconnected white wire (normally attached to the REGULATOR) and connecting the White directly to the the battery POS terminal.  Repeat the B and C tests.  However, if at any time the battery voltage rises above 15V, stop the test.  Such an indication would prove the charging system capable of maintaining a known good battery.  If this test never achieves 15V, then there is a wire/connector issue in either the ground path leading back to the battery NEG terminal, a wiring/ connector issue withe the rectifier RED path to the battery POS terminal, or you made a mistake in D through G.

I - (not used, can be confused with L)

J -  The only parts that remain to prove or expose are the REGULATOR (in active mode) and the electrical path between the battery POS terminal and the black wire that connects to the REGULATOR.

K - Lying to and starving the regulator
The regulator can only do its job correctly if it gets a proper voltage report of true battery voltage status.  The Vreg monitors the Black wire for this status.  Measuring the voltage lost between the Battery terminals and the Vreg connections identifies problems that are not really the charging system's fault.
Two connection paths must be checked, the Battery POS terminal to the Black wire connection at the VReg, and the Battery NEG terminal to the Green wire connection to the Vreg.  A volt meter can measure these losses directly by placing a probe between the two identified points, Black path and then the green path.  The numbers are summed and the error seen by the Vreg quantified.  Anything over .5V loss is cause for concern and anything over 1V is a certain issue to be corrected.  Each connector, terminal, fuse clip, or switch in the pathway can cause voltage reporting loss.

The regulator also passes the received voltage on to to the Alternator field coil to create a magnetic field within the alternator,  The voltage level determines the strength of the magnetic field and the maximum output capability of the alternator.  Therefore, starving  the Vreg of true battery voltage leads to reduced max output capability of the alternator.

L - regulator operation/verification.
  The Vreg sends voltage to the alternator field in response to measured voltage which is battery state of charge.  Any voltage at the battery of less than 13.5V sends full black wire voltage to the alternator's white wire.  The alternator output will vary with RPM, even if "told" to produce max power by the Vreg.  If the alternator has enough RPM to overcome system load, any excess power is routed to the battery which will raise the battery voltage (slowly if depleted and rapidly if nearly full).   When the battery reaches 14.5V, the regulator reduces the voltage to the alternator, reducing output strength and preventing battery overcharge.  If the battery exceeds 14.7V, the regulator clamps the alternator field coil power to zero (0V), effective shutting off the alternator.

Because, there is electrical load from the system, an alternator that is not producing power allows the battery to deplete and the voltage falls.  The Vreg responds by turning the alternator back on in accordance with battery state/ charge level.

The Vreg state changes can be monitored/verified by observing the battery voltage state, and the White wire to the alternator field.  (Two meters are handy for this.)  The "trip" voltages can be adjusted with the adjust screw, while changing engine RPM and electrical load that the bike presents to the battery/charging system to "make" the battery reach the voltage levels need for the set trip points.  IE. with load reduced (lighting off) and the engine above 2500 RPM, a charged battery will attain 14.5 V.  Anything above that and the adjust screw needs to be backed out to keep the battery safe from harm.
The shop manual outlines bench set up mechanical adjustments that should be performed on unknown or tampered units.  These should be resolved before final trip point adjust tuning.

Note that while the system is working, the Vreg can change states rapidly before your very eyes., changing 5 times or more while you blink.  Therefore, you may have to mentally average values measured on the White wire if your selected meter doesn't do that for you.

I've done a few additional tests, but I'll go through the above list:

A-> I'm at 12.43V, that's not fully charged I know, but I'm going to put it back on the charger. It was fully charged just a while ago and the battery acts like a very healthy and holds a charge. Still the bike kills it. I'm going to charge it up again and run through the tests again.

B-> The voltage never rises above 12.47V, at low RPMs its around 12V.

C-> The lighting system is no switchable on this year.

D-> I have tested the rectifier it's fine and I have a spare I made and the results do not change.

E-> The field coil reads a tiny bit high at 5.2 ohms, but that seems acceptable. This is both with the engine hot and cold.

F-> The stator windings read too high at 1 ohm. However, each winding reads exactly the same. Since these rarely go bad and for all coils to fail at the same time with the same readings it seems more like inaccuracies in my multimeter than and actual problem. This is the most suspect static reading on the whole system.

G-> I've cleaned and checked the gap in the regulator. The points have basically zero resistance.

H-> I shorted the white wire to the battery positive terminal, You could see a rise in voltage when it was connected, but it still was too weak.

J-> I did find some voltage drop at the regulator, so I ran a wire from battery positive to the regulator and it had no effect.

K-> I'll go through the connectors to make sure that I'm getting enough good contacts, but with a direct supply to the field coil from the battery, it will not charge just the same.

L-> I'll verify once I get some output.


I'm going to try again with a fully charged battery, but so far the biggest suspect is the stator windings. Most bad coils from what in understand will show an open circuit or a short circuit to ground when heated, but I'm not getting that.

Anything I missed?

[kaptainkid1]

Just fixed my charging problem and it turned out to be the ignition key housing it was dirty contacts. I sprayed carb cleaner in the back of the key body housing. If you pulled the key mount out and pull back from the rubber cover you can access the hole and spray cleaner in your.
I have a 1974 Honda CB550 and it sat out side for years and was a barn find. So oxidation can build up on all the contacts and you should take wire brush and clean all the terminals. Don't forget to clean under run/off switch with carb cleaner too.
Here is the thread of my experience.
http://forums.sohc4.net/index.php/topic,171783.0.html

Good luck!

[TwoTired]

A-> I'm at 12.43V, that's not fully charged I know, but I'm going to put it back on the charger. It was fully charged just a while ago and the battery acts like a very healthy and holds a charge. Still the bike kills it. I'm going to charge it up again and run through the tests again.

That's about a 75% charge.  It will take the bike some time to make the voltage go higher.  And, that's relative to the electrical load placed on the alternator. If we assume you have absolutely no component changes from stock, it will still take an hour or more at higher RPM to bring the voltage back up 13.8V.

B-> The voltage never rises above 12.47V, at low RPMs its around 12V.

How long did you hold the revs?  Never is a very long time.  You have that much patience?

C-> The lighting system is no switchable on this year.

Um... It still has a headlight fuse you can remove for testing.

E-> The field coil reads a tiny bit high at 5.2 ohms, but that seems acceptable. This is both with the engine hot and cold.

Did you subtract out the meter's lead resistance?  Do you have a quality meter that is rated to measure low ohms correctly?

F-> The stator windings read too high at 1 ohm. However, each winding reads exactly the same. Since these rarely go bad and for all coils to fail at the same time with the same readings it seems more like inaccuracies in my multimeter than and actual problem. This is the most suspect static reading on the whole system.

Again.. Did you subtract out the meter's lead resistance?  Do you have a quality meter that is rated to measure low ohms correctly?  Unlikely a stator problem, if it hasn't been physically abused.

G-> I've cleaned and checked the gap in the regulator. The points have basically zero resistance.

That's good.  Did you tweak the adjustment screw?

H-> I shorted the white wire to the battery positive terminal, You could see a rise in voltage when it was connected, but it still was too weak.

Was this still with the battery partially discharged?  You wish to see the battery instantaneously full?

Did you subtract out the meter's lead resistance?  Do you have a quality meter that is rated to measure low ohms correctly?

J-> I did find some voltage drop at the regulator, so I ran a wire from battery positive to the regulator and it had no effect.

Did you vary the RPM?  Battery still not full?  Did you notice ANY rise in voltage.  What WAS the voltage?

K-> I'll go through the connectors to make sure that I'm getting enough good contacts, but with a direct supply to the field coil from the battery, it will not charge just the same.

Sorry, the unit must obey the laws of physics.  If the components test good, and the connections are good, the unit absolutely MUST function as designed.  You must be omitting something


The charging system is never powerful enough to instantaneously change the voltage of a good battery hungry for charge.  The battery is supposed to be stable.  the charging system just refills it when it can.  Can't fill the pool very fast with a garden hose.  But, you can drain it much faster with a fire hose or aqueduct.

Cheers,

[scottly]

E-> The field coil reads a tiny bit high at 5.2 ohms, but that seems acceptable. This is both with the engine hot and cold.

At what points in the harness did you test the field? Remove the white lead from the regulator, and measure the resistance from the wire to the battery negative terminal; it should be the same 5.2 ohms.

[titan joe]

As far as the switch, I tore it apart a few months ago, cleaned and applied new dielectric grease, so it's as good as it gets.

Right now the bike is on the charger for the night to get a better baseline.

All my resistance numbers were accounting for lead losses.

I'll try to get some numbers with the headlight fuse pulled. The only electrical modifications are the H4 bulb I am running and a relay to run a the ignition more directly off the battery and supply power to a voltage meter and my wideband oxygen sensor controller. I'll disconnect those for future tests and see how that effects charging.

As far as wait time to collect data points, I just set the idle at about 4500 rpm and would run my tests there for about 30 seconds to 2 minutes.


Also, I never use the starter because the solenoid doesn't work. So I never have that drain on the battery.

I tweaked the adjustment screw on the points, but they aren't cycling. They are remaining in the rest position which is max charge. I can press on the arm and force it to switch and watch the voltage drop down to about 11.9 volts. Running battery voltage directly to white wire is full charging power, so I think that eliminates the regulator as the problem.

I think I'll try again with the sensors not powered up.

Well, now I'm thinking that I have too much load on the system. I read this, and look, it's TwoTired again with his knowledge:

I don't think you understand the regulator's function.  It only indirectly maintains the system voltage.  The Battery state is the primary dominant factor in the system voltage.  And the "regulator's" primary function is the keep the battery from overcharge when and if the alternator can make more power than what the bike uses.

Some basics.  The 550 has a 150 watt peak alternator output.  It can only produce this much power if it's magnetic field is driven to full strength AND the rotor is spinning fast enough.
At idle and with full field strength, the alternator can only make about 1/3 of peak capability, or about 40-50 watts.
The stock bike (you never told us if your bike was stock, electrically) consumes about 120 watts whenever the key switch is in the ON position.  What isn't produced from the alternator is drawn from battery storage until it is depleted.

A fully charged and rested battery will have 12.6-12.8 volts without a load attached.  The voltage will fall lower than this when loaded, and drop lower as the storage capacity is depleted.  (This is why charging systems are tested only when a known good, fully charged battery is present in the system.) 

When the battery is recharged, it should not be allowed to attain more than 14.5 Volts peak.  More than this and the battery can be damaged, and that is the true function of the regulator, to never allow the battery voltage to climb higher than 14.5 V.  The regulator does this by controlling the field strength of the alternator.  When the battery voltage falls lower than about 13.2V, the regulator applies full battery voltage to the alternator field, allowing the alternator to be all it can be at any given RPM.  Clearly if the the alternator is putting out 50 Watts and the bike is using 120 watts, there is no power excess to raise the battery storage level, and the voltage level can never reach 14.5 V.

On the other hand, if the engine is revving at 5000 RPM, the alternator should be making 150 Watts, and with the same bike load, there is 30 watts excess to provide restorative energy to the battery and raise the voltage commensurate with its charge state.  If depleted, it can take 10 hours or more to reach full charge state and 14.5 V  (again, this is why you must test with a known good fully charged battery.)  Once the battery is restored to full storage capacity, the Voltage "regulator" notes this and reduces the voltage sent to the alternator field, which lowers the alternator output strength and prevents overcharge damage.

Essentially, the alternator can provide up to 13 amps and the bike uses 10 of them.  The battery can produce or consume 100's of amps, depending on it's charge state.  IT is the dominant factor in the bike system voltage, so you MUST be mindful of its charge state when examining the charging system.

 I will say that the Cb550 is particularly hindered by headlight "upgrades" and ignition system changes, that the 750 can usually tolerate.

Of course connectors, fuse clip terminals, and switch contacts can degrade and consume voltage before it can get to the alternator field, which can make a 150 watt peak alternator put out 100 watts peak due to voltage starvation.  Pretty much all these things can be properly diagnosed with proper application of multimeter probes.

Cheers,

After a little sleuthing:
Stock bulb runs a 40/50 watt bulb
My H4 should be running 55/60 watts.
That's 15 watt max increase.

My wideband sensor has a typical draw of 18 watts but a 30 max.

That relay probably consumes a watt or two to at my minimum I've got a 30 watt increased load on the system. That's a 20% increase on the system in the best case. And that's only when max power is available, probably 5k or more.

Luckily, the wideband is not going to be permanent resident. I'll have to test without the accessories.

At what points in the harness did you test the field? Remove the white lead from the regulator, and measure the resistance from the wire to the battery negative terminal; it should be the same 5.2 ohms.

I good test too, I'll do that as well, it's easy enough.

[titan joe]

I've got charging!!!!

I got an LED H4 bulb which only draws 18.6 watts. Now with the wideband controller and the headlight running I have plenty of power. I had to tweak the voltage regulator, but I charge now. I'm surprised how much the voltage level jumps around. I've seen it spike pretty high at random times when engine speed isn't that high and then end up lower. I think that it has a lot to do with the switching speed of the regulator. I saw 16.9 volts at one point today, but it never got that high again, I'd see 14 as the average. So it seems like I had the system overloaded.

[dave500]

even with the stock system it can only supply so much,a 50/65 h4 shouldn't overload it,tinkering with the reg might've helped in that reguard?their an old reg now and more modern electronic types truly give a more solid and stable voltage.

[TwoTired]

If the regulator allowed a 16.9 V level, it is certainly adjusted wrong. It should never allow this.

Take as much load off the electrical system as you can (pulling fuses).  With a fully charged battery and the engine revving adjust from 14.5 V max.  This way you won't cook a battery with overcharge.

If the alternator undercharges when the load is back on, you have wiring issues or load issues that adjusting the regulator won't fix.   Most importantly the regulator must "see" the true battery voltage at it's terminals.

Cheers,

[titan joe]

The strange thing is that I only see higher voltages than normal when I'm not revving the engine very much within the first 5 minutes of running the bike. Most of the time I see about 13V on the system. I can watch the regulator do its switching action with my meter while I ride the bike.

In response to Dave, I'm also running a wide-band controller that pulls another 18W. I think that was adding up.

[scottly]

The stock mechanical regulator causes voltage spikes due to it's switching nature. This is less noticeable with an analog meter, as they display more of an average voltage. A digital meter takes "snapshots" of the voltage at intervals, then analyzes the samples and displays the reading for that instant in time. If the "snapshot" is taken just before the regulator points open, it will display a much higher voltage than the average. I've seen over 16V spikes with the stock mechanical regulator and an LiFe battery, and switched to an electronic regulator as soon as I could after seeing that.

[titan joe]

I've been thinking about getting a solid state regulator. I have a few I could temporarily adapt from some Bosch car alternators.

[Deltarider]

The stock mechanical regulator causes voltage spikes due to it's switching nature. This is less noticeable with an analog meter, as they display more of an average voltage. A digital meter takes "snapshots" of the voltage at intervals, then analyzes the samples and displays the reading for that instant in time. If the "snapshot" is taken just before the regulator points open, it will display a much higher voltage than the average. I've seen over 16V spikes with the stock mechanical regulator and an LiFe battery, and switched to an electronic regulator as soon as I could after seeing that.

I can confirm this. Digital meters can give funny readings. An analogue meter gives a truer indication of what is happening. Those that check their charging system, should be aware of this before they suspect bad connections and start tampering with adjusting regulators, replacing parts and what not.

[dave500]

I've been thinking about getting a solid state regulator. I have a few I could temporarily adapt from some Bosch car alternators.

ive used bosch re57 for years,always stable voltage.

[titan joe]

Back on this again. I thought things were going pretty well with my newly adjusted system, until...

I was riding up a canyon with a friend and checked the voltage of my system and it was at 10.9! It charges around town, but at highway speeds (about 4k and up) it just quit charging. 3.5k and below it charges strong (down to where charging tapers off near idle). It's like clock work. I'd also sometime see over 15V when putting around town shortly after startup. I've been thinking that the voltage regulator has an issue, but I'd rather not throw parts at it and go solid state. I like that Bosch Re57 regulator so I may end up trying to find one. They seem to be more limited to the Oz market. Kinda weird.

So to test the system I dug up a voltage regulator from my 71 Volvo. After a check of the wiring it uses the same set up. In this case, power and ground and a high side switch for the exciter field like the bike does. The defining attribute is that the exciter winding connects to ground on one end. The other regulators that I have that are solid state and internal to an alternator use low side switching. The defining attribute to these in the diagrams is that the exciter winding connects directly to the 12V positive source and are switched on the grounding side.

The result is I have good stable voltage to about 5k, but from there is creeps into the super 15V range. I'm thinking that the car regulator is just designed for a much larger system and the resistor for the low charge is just not as big as it needs to be. Nevertheless, I can clearly see that the rest of the system has got the gusto to charge all I need.

So at this point I'm either going to get an RE57 or find me the right P MOSFET and build a regulator.

[dave500]

an re55 is the same but only has the d+ and df terminals,the body is earthed.

[TwoTired]

I have several bikes using the stock charging system, that still work after 40 + years of operation.

What is the impetus for not using the stock components proven to work?

Cheers,

[titan joe]

You make a good point, but I've been through the cleaning and adjustment procedure and seem to obtain unreliable results. I'd like it to work. I'm going to have a closer look, but I can't even make sense of the way that it is acting. I cleaned the points, adjusted the gap and set up the output. It even seemed to be pretty happy for a while, but now no one can explain why when more power is being generated why the regulator charges less. If I can wrap my head around what it's doing wrong, I'd be glad to fix it. I still plan on investigating reinstalling the regulator, just to find out what really is going wrong.  Any ideas are welcome.

[TwoTired]

May I ask what procedure you used to set the voltage adjustment?

Cheers,

[titan joe]

Sure. Today I spent some time going through the regulator again.

First, It had a lot of pitting in the very top contact. I sanded all contacts, adjusted the core gap to about . 030" and then the point gap to .008". Stuffed it back on the bike and ran it up to about to speeds of 4k and saw it was getting to high (like over 15 volts at sustained 4k rpm and continuing to rise. So I crank it down a bit and get it so at 4k rpm it stabilizes at 14.7V. Sounds acceptable. I try some higher RPM to see if it continues to hold, it seems to, so I go road testing next. Immediately going in a 35 mph I see the voltage creep up and up to over 16V! It's not bouncing around, it was a steady creep. Then it seems to settle down, so I continue my ride. In a 60 zone I see mid- 13V. I race up a mountain and see a little lower voltage in the low 13's. When I get back home I decide to increase the regulator output a little more since now it is definitely at running temp. I still see 14V+  around 3000 to 3500 rpm, but see lower at 4k and above. After a readjustment I'm getting right around 14V getting out of town and the I hit the interstate with sustained RPM's above 5K and voltage drops to a little below 12.5V on average. I see it occasionally spike to about 12.6V, but I see it also go to about 12V even. I come back into town and have lower engine speed and I'll get 14V again around 3k rpm. I could go higher with the regulator, but I don't want to see the overcharging by turning it up. It should go to a descant average voltage and maintain it instead of dropping voltage as engine speed increases.

I did notice very bright arcing at the contacts when they open. That doesn't seem good for longevity of the points.

Also, the battery is fully charged and I am running an LED headlight, so that lightens the electrical load substantially.

If there is something I am missing I can try again.

[Deltarider]

For a reliable test I recommend an analogue voltmeter over a digital one.

[TwoTired]

Thanks for the description, Joe.

Sandpaper abrasive particles are harder than the contact material.  And, by design, they are sacrificial in that particles are lost when used.  These lost tiny particles embed themselves in the contact surfaces, and stand proud as the surface wears.  These particles are not conductive, and reduce the current carrying capacity of the point contacts.  This leads to issues during the make/break cycle and one symptom is excessive arcing.

The phone companies used to use literally millions of points contacts in relays needing periodic maintenance, and found reductions in attention needed by using files instead of abrasive grits.  The files do leave tiny fragments behind embedded in the contact surface, still.  But, not as many and being metal, these particles are metal and don't reduce contact conductivity.

All this to say, don't ever use sandpaper on electrical points contact surfaces, only metal point files.  This may be a contributor to why your regulator won't stay stable in use.

Second point to be made is how the "voltage regulator" functions in circuit.  It only regulates state of charge to the battery, and that task is limited to keeping the battery from over charge.  The bike's system voltage will always follow the state of charge of the battery.  The alternator does not have the power available at all rpms to provide all electrical demands from the bike.  The battery is the buffer, and will lose state of charge level while making compensation for alternator weakness.
To that end, think of the vreg as an upper limit safety to ensure the battery doesn't get cooked after it has been totally recharged, and the alternator IS making more power than the bike consumes (generally during long periods of highway cruising).

So, to do a vreg adjust in the shop set up a condition where the alternator can produce more power than the bike uses.  Disabling lighting helps a lot.  And ensure the battery is in a full state of charge, and doesn't need any more current.  Then set the vreg to limit the charge voltage to 14.5 - 14.7v.
Thereafter, the voltage regulator can never allow the battery to be "boiled" while riding about.  The point gaps take care of other state of charge changes and electrical load variations in a healthy charging system.

The other dependency for proper vreg function is that it receives true battery state of charge indications on that black wire connection.  That  (and ground) is what it is using to make its alternator power decisions.  Losses in the pathway effectively 'lie" to the regulator and prevent it from doing its job correctly.  In line added resistance to the black wire to battery path alter the black wire voltage with changing load contitions.  Lights on can make the black wire voltage sense lower, lights off can make the black wire voltage higher.  This is a problem for vreg operation, but not a vreg problem. Stay off that vreg adjustment in an attempt to solve voltage problems.
Instead, fix those issues that make the black wire voltage lower, irrespective of battery state of charge.  I suggest you look at this first and make appropriate corrections before making vreg adjustments.

Hope this helps you get that bike (and yourself) amicable again.

Cheers,

[titan joe]

I hope I'm not coming off as unfriendly.

So from what I have gathered, I need points with no abrasive embedded in them and I need a good connection on the black wire.

I should have an excellent connection at my switch since I cleaned that really well when I first started chasing charging issues. I also doubt it's wiring since I made the positive lead (I solder everything) and with my car's regulator it charges in a very consistent manner. Still, It's only a few connections so I'll look for voltage drop and clean the remaining connections.

As far as I understand these regulators they work by switching the armature coil feed through a high current (and consequently string magnetic field) or a low current on (for a weaker magnetic field). They do this with the large resistors on the back and the points. The adjustment screw for the voltage puts more or less pressure on the points arm and you tune it to the magnetic field of the coil in the regulator. Essentially you find the spot where the coil's magnetic field is strong enough at 14.7V to overcome the spring tension and the welding of the points to break the circuit and switch to the low charge output. Since the points are is closer to the coil, the magnetic field is stronger at lower voltage and the system takes it's time to fall back from the cut-off voltage at about 14.7 and drops until the spring overcomes the magnetic force of the coil and it switches back to the full charging state. You get a hysteresis effect from this so it's not chattering thousands of time a second and ending your point's life time prematurely.

The plain inconsistency I find concerning. I don't want to overcharge at low speeds and undercharge at high speed.  Maybe the point themselves are to blame thanks to my clean up job. So I have a few things to try.

If not I'll be going solid state. I have everything to build one except an appropriate Pfet.

And make no mistake, I like knowing the old school way of doing things. I still have points ignition on my bike. I'm currently installing SU carburetors on a project car, because I like the simplicity and robustness of the old way. Little experiential information from people who actually have that is invaluable (like using a file on points instead of sand paper). That's why I keep coming back. I certainly don't know everything, but I sure am trying to.

[TwoTired]

Here is a way to test for vdrop battery to black wire path.

Place one volt meter probe on the battery POS terminal.  Place the other Vmeter probe on the black terminal.  Turn everything electrical for the bike on.  Read directly the error voltage present on that pathway between the probes.
Under the same conditions, probe between the battery NEG terminal and the Vreg Green terminal.
The sum of these two measurements is the error voltage seen by the Vreg in operation.

For fun, you can repeat the measurements with lighting off.  This should show less error Voltage in the battery to black wire pathway.

The vreg relay coil does indeed vary in strength with the voltage fed to it. (Black wire)
When voltage is too strong (High), the Vreg contacts effectively ground the field coil so the alternator can make no power.  With the contacts in limbo touching neither upper or lower contact, the big ten ohm resistor on it's back is inserted in the path between the black wire connection and the alternator field coil, reducing the alternator's power.  When black wire voltage is too low, the reg should pass full black wire voltage to the alternator field, making the alternator be all it can be at the selected RPM.  The adjustment sets the voltage where full power contact pulls free, to reduce the alternator power output with that 10 ohm resistor.
In my opinion, it's more of a battery safety device than an actual voltage regulator.

Given what you've typed in this thread.  It seems like there is a faulty connection somewhere in the charging circuit, that manifests during road vibration/operation.  I can't eliminate the possibility that it is even inside the vreg box.  That seems weird, but possible.

Cheers,

[dave500]

just go solid state,the old regs were all that was available in the day,be sure to check all other areas of your charging system first though,no feeble shorts to ground any where and so on.

[bryanj]

I had a 500 where the regulator points would "stick" in the middle (no charge) position occasionally and the engine has to be revving at over 3,000 to even stand a chance of charging the battery. Electronic regulators seem to be the fad nowadays but even a fractional bad earth or reversed contact will fry one totally in a split second