Magneto dead?

[DewCatTea-Bob]

" it comes down to no AC power being generated by either coil. "

____ Well that's rather strange. _ Unless of-course your alt.flywheel-rotor has become COMPLETELY loose !


" I spin the motor with the kicker and the best AC voltmeter I have reads zero volts on both coils. "

____ I'm now left to assume that you've also tried other than just THAT particular AC.volt-meter (which may be insensitive in this case),, and also, have made very sure that you haven't possibly checked the wrong wire-pairings against each other !? - Cuz as you're already aware-of, the lead-outputs of the two separate alt.power-coils should show NO voltage-readings between them, (as those separate power-sources are not inter-circuited together at all !).


Hopeful-Cheers,
DCT-Bob

[JimF]

I am now just more confused and thinking I should start over, checking everything.

I took the cover off:

in the cases.jpg

...and I guess I expected to see something wrong, or to be able spin the alternator/rotor/flywheel if it was indeed loose. But everything seems OK from a first order inspection. Was that a correct assumption?

I do have an old oscilloscope somewhere that might work. Do I need to watch for AC on that? I have one AC voltmeter that reads nothing, and the other reads milivolts. I am going to go back to the two meters, maybe put fresh batteries in them and just try two things again:

Measure the resistance of the windings from the alternator pigtails and measure the AC voltage output on my 'kick'over' rotation.

Bob et al, should I be able to rotate the alternator/rotor/flywheel (gold-colored in the picture, yes?) if it were loose?

Jim

[Rick]

an 'old oscilloscope' probably means analog, so it probably won't capture data for review like an newer digital scope would, that means it will need a continuous AC signal to display anything- pretty hard on your kicking leg, assuming you're interested in the AC strength.
A nice setup is shown at 5 minutes 36 seconds (5:36) into this video from Rick's Electrics.
http://www.youtube.com/watch?v=1C6t_MIm3J4
If you have access to a lathe you could probably build a fixture in an couple hours that would give you a nice signal.
Or, if your scope or meter have a 'peak hold' that you could trigger as the points open you could see how much energy is available at what(I think) is the crucial time. But, that's based on my understanding of DCT Bob's other posts, and I may not have it right.
Rick (not Rick from Rick's Motorsport Electrics)

[DewCatTea-Bob]

" I am now just more confused and thinking I should start over, checking everything.
I took the cover off:
...and I guess I expected to see something wrong, or to be able spin the alternator/rotor/flywheel if it was indeed loose. Was that a correct assumption? "

____ Well, I had expected to have the notions previously mentioned ironed-out, and perhaps some other stuff as well,, before you bothered to go-ahead & pull-off your left side-cover.


" should I be able to rotate the alternator/rotor/flywheel (gold-colored in the picture, yes?) if it were loose? "

____ Yes, the gold-colored wheel in your pic is the alt.flywheel-rotor,, and if it were really-loose,
then it could be held in-place while the engine is turned-over (with the rear-wheel rotated while in gear, [since the kick-stater is currently unavailable]), or,, if the rotor is loose (from the crankshaft), then when the rotor itself is forced to turn, it would fail to fully turn-over the engine.



" I do have an old oscilloscope somewhere that might work. Do I need to watch for AC on that? "

____ No, and Rick has addressed that now,already.


" I have one AC voltmeter that reads nothing, "

____ I wouldn't trust that one.


" and the other reads milivolts. I am going to go back to the two meters, maybe put fresh batteries in them "

____ I-myself only really trust the old-type of meters which don't require batteries, (as those of us who're old enough to be very familiar with both old & new meter types, have discovered themselves).


" and just try two things again:
Measure the resistance of the windings from the alternator pigtails and measure the AC voltage output on my 'kick'over' rotation. "

____ Your previously-stated resistance-readings are close enough, (the small amounts which I had mentioned to be outside of regular average-readings, is nothing to be concerned with !).
__ When you do your kick-starting voltage-output testing, it's possible to get the engine turning-over at a fairly good rate with multiple-kicks, providing that the spark-plug is removed from the cyl.head !


Hopeful-Cheers,
-Bob

[JimF]

Fresh batteries now in both DVMs.

One ohmmeter measures the ignition winding coil resistance to be 2 ohms while the other measures the same winding resistance to be 4 ohms.

Similarly one ohmmeter measures the lighting winding coil resistance to be 0.2 ohms while the other measures the same winding at 0.5 ohms.

I have tried using the lighting coil to power the ignition but there was no change in symptoms.

Currently neither meter displays any substantial amount of AC voltage on kick-over.

I may have to contrive to spin the rear tire while the bike is up on the table and in-gear to see if I am generating any voltage. I just don't understand how I cannot be since my coils are intact given the resistance measurements.

Thank you guys! I appreciate any and all theories (including Divine or alien mischief at this point.)

[DewCatTea-Bob]

" One ohmmeter measures the ignition winding coil resistance to be 2 ohms while the other measures the same winding resistance to be 4 ohms. "

____ Both of those readings seem quite high to me, your previous reading of 1.0-ohms was much more acceptable !
Still, I'd say that this has not reviewed a genuine malfunction.


" Similarly one ohmmeter measures the lighting winding coil resistance to be 0.2 ohms while the other measures the same winding at 0.5 ohms.

____ The average of these two readings is about normal for this alt.power-coil,
I'd most trust the meter with the "0.5" reading.


" I have tried using the lighting coil to power the ignition but there was no change in symptoms. "

____ Well okay then, then if your flywheel-rotor is found to be nice-&-tight,, then the related common-problem which most often occurs with these AC-powered Duke-models, is that the short/black-wire which grounds the white alt.wire-lead (through the normally-closed brake-light switch), becomes loose and thus-then fails to complete the intended circuit.
So the bolt/screw & nut which secure it's terminal-end to the frame should be checked-out. _ But then of-course, I would've expected that you've already checked-out the ENTIRE brake-light circuit-pathway, for such malfunction before now.


" Currently neither meter displays any substantial amount of AC voltage on kick-over. "

____ Well if your alt.rotor is indeed rotating along with the rest of your engine, then perhaps both of your meters may be too insensitive.


Hopeful-Cheers,
-Bob

[wcorey]

How about using a 'test light' rather than a meter?

Bill

[JimF]

I have to quit this for awhile. Too confusing... I need to step back for a day or two and clear my head.

I was spinning the rear wheel in gear and I saw "a" spark when I turned the lights out.

But not constant sparks. I kind of thought I traced it to the alternator pigtail connections. I rewired the alternator pigtails and it wasn't absolutely clear that I had fixed it. I thought the brake switch getting wet may have been problematic and since I had a new one I changed that too.

I buttoned everything back up but it would not start. After having spent a lot of hours this weekend on this and seemingly being no further ahead is a huge disappointment.

[DewCatTea-Bob]

" Too confusing... "

____ Is there anything in particular that's confusing for you ?


" I was spinning the rear wheel in gear and I saw "a" spark when I turned the lights out.
But not constant sparks. "

____ That occurrence is possible to happen with a loose flywheel-rotor.
__ Also, are you sure your ign.point's contact-faces are good & clean, and their mounting-plate is secured tightly ?
And also as well, is the ign.coil making good surface-contact with it's metal-bracket (which in-turn is also tightly-secured to it's place [without paint] on the frame) ?


" I thought the brake switch getting wet may have been problematic "

____ Only PURE 'H2/O' can act as an insulator, (such as on the switch-contacts), against electricity ! _ However 'water', (which is what H2/O is, once it has become contaminated with ANYTHING), would only possibly HELP-pass the alt.power with finding it's way to Ground, (as the stock-type brake-light switch normally does anyhow !). _ So even if that switch got really well soaked in water, it'd still make no real difference.
(Muddy-water could possibly insulate a bit, however.)


" I buttoned everything back up but it would not start. "

____ So the rest of us are left to assume that you actually did make-sure that the alt.rotor was still good & tight,
right ?


" After having spent a lot of hours this weekend on this and seemingly being no further ahead is a huge disappointment. "

____ Does your Duke have a kill-switch installed ?
__ Also, have you sprayed everything down really well with a good quality Gremlin-repellent ?


Hopeful-Cheers,
-Bob

[JimF]

I gave my brain a couple days off (from the motorcycle at least) and began to troubleshoot again. You might recall the motorcyle has not been able to start since it got drenched in a downpour (after which it started but just barely) and then got even more wet in a very wet ride home.

There was in the last troubleshooting episode a time or two that I got spark off the magneto with the kick starter, although I expected (and to some degree still do) to see spark more consistently in a darkened garage while kicking the engine over.

With so much of the magneto appearing normal (wiring is fresh and new, connections are tight, ohmic values are reasonable and the flywheel is secured) as part of a routine course of troubleshooting I had during the last session purchased aerosol electronic contact cleaner and spray-cleaned the points but it proved to have no effect. I had also run a dollar bill between the points to clean them as part of that general troubleshooting procedure. I assumed the points got wet in the heavy rain but they had to have been dry a day later.

I had also checked the points plate to make sure that it was secure, that is to say the timing had not inadvertently shifted and found it was very secure. I should also note here that I installed new just a hundred to two hundred miles ago along with a new condenser.

Yesterday I took a long hard look at the points but this time with a jeweler's loop. The loop revealed some kind of thin crusty contaminate on one edge of the fixed contact point. I expelled the item, whatever it was, and for the first time in a long time the was a hint that detonation was trying to occur during kick-over. I got a kick-back or two, and what sounded like the engine attempting to run for a millisecond.

During the first magnified examination I had also noticed some aberration that appeared as a miniscule dark spot in the surface of the stationary contact plate so I again jammed the jewelers loop back in my eye and with my face and a trouble light both about an inch from the points I am now surprised to see the stationary contact is pitted. There is a not-so-nice crater in the surface. As I said, these points were new just hundreds of miles ago, installed by me along with a new condenser.

It's as if the new condenser is bad. When I say the condenser was new, I mean it was "New-In-Box", but I don't mean it was fresh. The condenser is quite likely from the 1960s or 70s. I believe these things are by nature electrolytic capacitors which have some impregnated electrolyte inside. Perhaps the electrolyte dried up inside and reduced or ruined the effectiveness of the capacitor.

I think my next step is to change the points and condenser and try again.

Opinions are welcomed.....


NEW INFO

I have not yet removed the old condenser, but I have another new old stock condenser from an identically aged box and it reads 0.5uF. That's a half a microfarad. Much lower than I expected, but then I can't say on what I base it on other than the size of the condenser. Electrolytic capacitors that big usually have thousands of microfarads. Does anyone know if this is indeed too low?

Jim