Wiring-I'm Confused

[DewCatTea-Bob]

[quote= Ducatikid ...
" you are correct, I didn't need a new coil. "

____ Now why do you say that ? _ What has changed ?



" The old original is still good! "

____ You mean you also still have the original Green-label ign.coil ?




" I did get a reply from the rebuilder and he "reworked" the stator. "

____ How-so, in what way did he do such ?



" He said the service book (factory?) was incorrect about the stator wiring and he has to find his proper wiring schematic to tell me what is correct on my engine. "

____ He probably had assumed the same as Jim did, as I think the common service-manual only covers the more-common '40-watt' alt.model's stator-wiring, (which is quite different !),, and-so going by THAT, your builder/friend could've thus-then figured that the manual was wrong, when RATHER it simply was-not actually concerning the less-common '28-watt' version.



" Here's my numbers: yellow-.3 ohms, red-.4 ohms, blue-.9 ohms.
Ready for further instructions "

____ I now clearly recognize all those particular readings ! ...
Your blue = the stock-Yellow ;
your red = the stock-Red ;
your yellow = the stock-White, !!!
__ It seems that the builder rolled-the-dice in deciding which color of wire to match-up with each of the three alt.stator-circuits, (or-else he's profoundly color-BLIND),, but if not, there'd then have to be some really-GOOD (unknown)- logical-reasoning behind such obviously-illogical wire-color match-ups !
So I'd really like to learn-of what he was thinking his reasoning was for employing the particular wire-colors exactly where he had chosen to, (red-color excepted). _ And if there's no answer to that,, then I sure wouldn't care to have anybody like that, work-on anything of mine !


Hopeful-Cheers,
-Bob

[Ducatikid]

Bob, Here's the latest developements. I'm still not getting any spark. I have hooked up the blue wire and the wire from the points/condenser to the same side of the HT coil. I've connected a ground wire to the other side of the HT coil. The spark plug is new and the plug wire from the coil is new. No spark with a vigorous kick at the kickstarter. Have added either or both additional colors to the same post and nothing. BTW, I've made sure I'm getting good grounds too. Two questions: 1. does it make a difference to which side of the HT coil you connect my stator/points/ground wires to? 2. I'm now thinking it has to be the stator. Can it be that it's timed wrong on the crank the culprit? Or is it something else I'm overlooking? Thanks again, Tom

[DewCatTea-Bob]

[quote= Ducatikid ...
" I have hooked up the blue wire and the wire from the points/condenser to the same side of the HT coil. I've connected a ground wire to the other side of the HT coil. "

____ That is as it was meant to be, so something-else must be incorrect.



" does it make a difference to which side of the HT coil you connect my stator/points/ground wires to? "

____ No, not really,, (that would only alter the polarity of the ign.spark).
But I'd assume that you've already tried both-ways by now anyway, right ?
__ You still haven't confirmed what ign.coil you're using, is it the original Green-labeled coil ?



" I'm now thinking it has to be the stator. "

____ That's rather quite doubtful, as your posted ohm-readings were perfect.
__ Did you not yet learn from the guy who was said to have reworked it, exactly what-all he had actually done to the stator ?



" Can it be that it's timed wrong on the crank the culprit? "

____ That's a possible issue to consider next,, but when a mag.rotor is installed randomly, chances are that it will still be able to create at-least a slight sign of a spark, (as it would be quite against the odds that the rotor would be unintentionally timed at a time-point when the alt.power just happens to be at zer0-power when the points open). _ Have you tried the field-test of inserting one of your fingers (in place of the spark-plug), to feel for any sign at all of a HT-jolt ?
__ Did you not yet ask that guy if he had bothered to 'set' the mag.rotor properly timed when it was installed onto the crankshaft ?
Also, have you not yet test-checked for any power-output from the alternator, using an AC.meter ?



" Or is it something else I'm overlooking? "

____ You could possibly try-out an alternate power-source (instead of the alternator's) to learn whether the fault is within the ign.system. _ A constant DC-source (of at-least 12v) could be TEMPORARILY tried-out,, (but it can't be from a battery, as a power-source such as that would SHORT-OUT !), so a common transformer/power-adapter's DC.power (of at least 500mW) would probably fill the power requirement for the test. _ (An AC.source would-not be a useful power-source because it's power-pulses would-not be timed correctly, [and that's not an issue with a DC.source].)

____ Hope you next first post a response-post before continuing-onward.


Hopeful-Cheers,
-Bob

[JimF]

Here's an interlude while you are waiting for Bob's next answer...

There are several simple steps you take to test your metal can type coil:


It is actually two coils in one can. One coil, called the primary, induces voltage into the other coil which we call the secondary. The secondary coil is the coil that generates the high voltage.


Your coil likely has two tiny terminals on the bakelite top equidistant from the center of the coil where the high voltage wire to the spark plug pops out. Those are the two opposite ends of the primary coil winding.


If you have an ohmmeter you can measure between the two terminals with all other wires disconnected. It's important to disconnect the wires going to the coil otherwise your ohmmeter will also include the resistance in those wires and what they connect to making the readings almost nonsensical. Because there is so much wire inside the coil wrapped round and round, and because the gauge of the wire is so small to make this coil of wire it fit in the can, even though you are just measuring across two ends of the same wire it will read several ohms. On open (infinite ohms) reading would tell you to throw the coil in the trash.


Likewise you can do the same thing with the secondary (high voltage) coil. You need to measure across the two ends of the coil, it 's just the the two ends are not obvious terminals like you used for the primary. If you unscrew the cap around the thick high voltage wire going into the coil, you can pull the wire out and you will see a metal-coated basin with a center pin in the middle that skewers the high voltage wire. That's one terminal representing one end of the secondary coil. The metal can which is conductive is the second terminal, that is to say the other end of the secondary coil wire. Measure the resistance. It will be much higher than a few ohms perhaps in the thousands of ohms, but none the less it should have a resistance value.


Here again an open (infinite resistance) would mean throw the coil away.


You could measure from the metal spark plug cap connection at the end of the spark plug wire if you don't want to take the cap off the high voltage terminal of the coil. However, if there is a resistor embedded in the wire it will add to the resistance of the coil so expect that the coil resistance reading could be quite high as a result. Also, if you get an open circuit (infinite resistance) you won't know if its the coil that is open or the high voltage wire or the spark plug cap that is creating the open circuit.


This test will give you some confidence in your coil but if you debug everything else and still aren't getting high voltage you could have a coil that fails internally. It will read good to the ohmmeter, but perhaps broken down insulation on the wires inside or moisture that has crept into the coil could be allowing the high voltage potential to arc inside the coil itself and thus never giving the spark plug the voltage it needs to jump a spark across its electrodes in the cylinder head.


Using a spark plug, a spark plug wire and the coil under test along with a battery you could test to see if the coil is generating high voltage but the test requires some small amount of preparation and a large amount of caution as the high voltage could knock you on your butt or worse.


On a side note I have asked Bob to write a book... In retrospect I should have specified "a book about Ducati singles" as for all I know he may have accepted my request and he could be diligently typing day after day and be halfway through the next great American novel.


Jim

[Ducatikid]

Thanks Guys, and Bob, I bought a new 6V HT coil from a local bike workshop. Put that one in place of the original and didn't get any results. Can I use any 6V coil or does it need to be a specific one intended for an alternator/magneto??? Also, I man'd up and grabbed the main leads from the stator (one at a time) while turning over the motor and felt no electrical pulses at all.........How do I set up this multimeter (connections & etc) to read any AC current??? The builder said he replaced the leads as the old ones were rotted. He said the stator checked out ok on the bench. I should be getting my fingers/hands shocked holding on to the stator leads.....I'm not! I still reason there is a problem with stator/wiring. Can the possibility be that the rotor magnets are weak??? Jim, I get 3.6 ohms between the 2 separate side posts. 11.12 ohms thru center (inside) post and to each side posts. Both readings are the same. There is no resistence or continuity from the center post to the can (this is where you lost me on that test). Again, I'm an electrical dummy.......What can I say........I appreciate all your help guys! Tom

[DewCatTea-Bob]

[quote= Ducatikid ...
" I bought a new 6V HT coil from a local bike workshop. Put that one in place of the original and didn't get any results. "

____ The "6V" HT.coil you got is actually meant for an ign.system that's meant to be run with a 6volt-DC.battery-system. _ Still however, (if all was connected-up properly), a spark (of some value) ought to have shown-up.


" Can I use any 6V coil or does it need to be a specific one intended for an alternator/magneto??? "

____ As I had already indicated before, the ign.coil need-not have it's primary-circuit 'rated' for handing six-volts ! _ As your 160-ign.system's power-source is-NOT '6-volts' (or ANY specific voltage) !
__ Ign.coils are all pretty-much the same in that they are all merely a transformer which steps-up low-tension current up-to High-Tension current, and they come with differing ratings depending on the primary's ability to handle current (without getting too-hot), and their internal turns-ratio (which determines the desired spark-voltage).
The 160's original 'Green-label' ign.coil was designed somewhat differently as it's intended to handle the alternator's VARYING power-output,, meaning that it has to have a sufficient turns-ratio which can produce a usable spark when the alternator produces relatively little power-juice for it's primary-circuit, YET-also it's primary-winding has to be designed to be able to cope with the much higher alt.power produced when the alt.rotor is spinning up-near red-line, (so as to avoid otherwise possible overheating of the ign.coil's primary).
So the original 160-ign.coil had to meet a number of spec.conditions in a rather more balanced & compromised set of conditions.
(It should go without saying-so, that the 160's [magneto-like] ign.spark's power-intensity grows STRONGER, as eng.revs climb !)
__ A '6-volt' rated HT.coil may tend to handle the power-current better since it's primary-winding is expected to have a relatively thicker-gauge,, but then also, it's turns-ratio may produce voltages (at high-RPM) which are high enough to overwhelm the internal insulation of the secondary-winding, (thus possibly shortening it's life-span).
So providing that your original-stock 160-HT.coil is actually alright, then of-course IT would be your preferred-choice to continue with, (cuz it seems that IT's not the source of your issue, since the new HT.coil showed no difference).



" Also, I man'd up and grabbed the main leads from the stator (one at a time) while turning over the motor and felt no electrical pulses at all......... "

____ There's likely two reasons for that absence... First you'd need to have your other-hand touching the motor-ground,, and second, the generated voltage would then (at kick-over revs), be too-low to be felt ! _ You'd need the engine/alternator to be turning-over about 4000-RPM or higher to feel any voltage-juice, as it takes at-least 30-volts to begin feeling any pulse-tickling through your skin.
So I gather that your hands were not wet during that test, as they'd likely need to be in order to feel any pulsing with under 24-volts.
To do such manual type juice-testing at kick-starting rev.speeds, you'd need to use your wet-tongue to feel for any such low-voltage juice-zapping.



" How do I set up this multimeter (connections & etc) to read any AC current??? "

____ I take-it that you just got your first new multimeter for your own-self.
__ Anyhow,, set the meter to 'AC' & at it's under 10-volt (but not under .1-volt) range-setting, (or whatever AC.range-setting it happens to have that's between .5 & 10 volts). _ Then connect one on the meter's leads to the motor-ground, and it's other lead to one of the alt.stator's three wire-leads, (one at a time).
Then kick-over the engine as fast as you can (with it's spark-plug removed from cyl.head). _ And note the AC.voltage-readings you obtain from each of the three different circuits.
Your blue-wire (which must be the original yellow-alt.wire), should produce the highest voltage-reading with the least effort of spinning-up/cranking-over your engine, and IT might exceed 10-volts with your greatest kicking-effort.



" The builder said he replaced the leads as the old ones were rotted. "

____ That's quite common, (but I still question his reasoning for his particular choice of color replacements !).



" He said the stator checked out ok on the bench. "

____ As your-own testing has confirmed !



" I should be getting my fingers/hands shocked holding on to the stator leads.....I'm not! "

____ Actually of-course NOT - as I've just explained above !



" I still reason there is a problem with stator/wiring. "

_____ Just WHY do you keep thinking that ? ...
Your-own meter-readings (so far) confirm they're okay,, so you shouldn't question that so much, until possibly after you've gotten absolutely NO voltage-readings from the alt.stator-wiring.



" Can the possibility be that the rotor magnets are weak??? "

____ Yes but, even when weak, there should still be some amount of measurable power-output.
It's just that the power-output may-not be correctly 'timed' for when the ign.spark has to be created.
Have you yet asked your builder/friend if he had at all thought-of being concerned with such alt.rotor-timing issues ?



" I get 3.6 ohms between the 2 separate side posts. "

____ Is that with your new-HT.coil or the stock-coil ?



" 11.12 ohms thru center (inside) post and to each side posts."

____ That would indicate a circuit-pathway between the primary & secondary winding-circuits.
__ Have you preformed that same circuit-test on both of your HT.coils ?



" There is no resistence or continuity from the center post to the can "

____ But there's supposed to be a secondary-circuit between the HT.electrode & ground !
So perhaps you did-not have your ohm-meter re-set to a more suitably appropriate range-setting... As while the range-setting for measuring the HT.coil's primary-circuit ought-to be set at the 'x1-setting',, the setting for measuring it's secondary, ought-to be set at the 'x1000-setting' (or 'x10k', or even '100k', range-setting), in order to 'scale' any ohm-reading that's as high as is expected from the HT.secondary-winding.
__ Anyhow,, that's not the actual-case with BOTH of your HT.coils, is it ?



" (this is where you lost me on that test). "

____ I'll leave this for Jim to iron-out with you.



" I'm an electrical dummy "

____ With your very-own new multimeter, you then may-not be-so for long.


Hopeful-Cheers,
-Bob

[Harvey]

That's one terminal representing one end of the secondary coil. The metal can which is conductive is the second terminal, that is to say the other end of the secondary coil wire. Measure the resistance. It will be much higher than a few ohms perhaps in the thousands of ohms, but none the less it should have a resistance value.
Jim

Giday Jim, the secondary circuit is from the center terminal to the positive primary terminal. The case is not connected to the windings. Some have plastic cases.
Cheers.

[JimF]

Thanks Harvey. I stand corrected.

Ducatikid, I was wrong about how to measure the high voltage winding's resistance. You must measure between the high voltage cap and one of the primary terminals.

Also, don't try to read AC current (amps.) This is a difficult thing to capture on a meter, and it only makes sense to try to read current (amps) in static DC systems where a constant value of current is flowing. Your AC system is dynamic; it's constantly changing directions. The AC current will flow one way, then the other making the average current flow "zero."

Also you have to have a load so current has some path to flow, and then the meter has to be "in-the-line" so the current flows through the meter and through the load. Lastly the current reading abilities of most meters is limited to about 2 amps or less.

You might try to measure AC voltage which should be present regardless of load. It too will average "zero" volts but the meter should capture the RMS value of the AC voltage which will tell you that voltage is present.

Don't try to measure the high voltage output of the ignition coil. It will fry the circuitry of your meter and ruin it.

[Ducatikid]

Bob, As serious as this situation is to me.........Your humor makes me smile! Thank you! No, I'm not going to hold any lead to my wet tongue whilst kicking the engine over..........especially as hard as I can!!! Yes, this is a new craftsman autoranging multimeter which is digital. I connected the black test lead to "com" and moved the red test lead to "V" (the other port for the red lead is a F/A/))))/an arrow with a plus/ohm) I turned meter on and used the range button to move the decimal point all the way to the right of the scale i.e. from .000 to 000 and kicked hard with the connections you instructed. the meter is set to V AC. Blue lead-7, red lead-3, yellow lead-2V. Also, the test numbers on the HT coil was for the original Ducati Elettrotechnica coil. The same testings on the new 6V HT coil were double those numbers. Ok, my friends, I'm ready for the next experiment!!! Dr. FrankenTom

[DewCatTea-Bob]

[quote= Ducatikid ...
" Your humor makes me smile! No, I'm not going to hold any lead to my wet tongue whilst kicking the engine over.......... "

____ While I had thought that perhaps that might make SOMEbody crack a slight grin, that live-juice test was actually something I-myself have indeed tried out in the-field when I had no test-meter (as a teenager). _ All ya get at kicking-revs, is a slight tinglely-bite of AC.juice, which the tongue can easily feel, when damp-fingers can't. _ As it's really rather low-voltage (and a 9v.battery would sting the tongue with a harsher bite than that) !
Of-course it's not a test I'd recommend at much higher eng.revs, (but if some back-woods/hick-type actually tried so, I'm still sure that he'd be found still breathing the next day).



" Yes, this is a new craftsman autoranging multimeter
the meter is set to V AC. Blue lead-7, red lead-3, yellow lead-2V.

____ Okay then, your higher-reading of 7-volts from your blue-wire confirms that it's the same alt.stator-circuit as the original Yellow wire-lead.
Your test for AC.production confirms that the alt.stator itself must be alright. _ So if your ign.points-circuit is not shorted anywhere (and thus turns on & off depending on the closure-action of the points), then it seems that the alt.rotor must be mistimed to the crankshaft, (which has the alt.power-output occurring at times when the ign.system doesn't require it).
__ Have you not-yet asked your builder-friend whether he had paid any attention to the alt.rotor timing-issue, when he installed your flywheel-rotor ??


Hopeful-Cheers,
-Bob