450 RT Magneto

[DewCatTea-Bob]

" I will carefully recheck tomorrow. "

____ Yes, please do (whenever soon as convenient).

____ BTW, I should've mentioned before now (for others interested in 450R/Ts), that many (if not most) 450R/Ts came-stock with (at least) one other 4-pole type alt.wiring set-up... That one has only 2 alt.wire-leads, 1-White (for ign.coil) & 1-Red (for headlight), and both of THOSE alt.wire-leads have CLOSED-circuits in ANY case -(between both ground & each other!).
Also, about 5-years ago I made contact (through eBay) with some R/T-Duker who claimed that his R/T had a "black" alt.wire-lead along with a yellow, (or a yellow plus a white, I don't exactly recall).
Anyhow, (even though I've never seen one with any black-alt.wire), it's certain that the 450R/T-models came with both 3-wire & 2-wire alt.wire-lead set-ups. _ And I believe that the early 1971-models (which btw then retailed for $1189 !), came with the 2-wire version (since it only had a head-light & plate-light), while the later '71s & all '72s came with a full Light-Kit for street-legal operation.
__ It ought be helpful to know the motor-number on yours to better determine the specifics of your particular R/T-model. _ (Indeed it would be even further helpful if all of those of us with 450R/Ts would report [here] their R/T's motor-number -[at least first 5 digits], and alt.wire-lead colors !!) _ My own 450R/T motor has the number 455066 and came-stock with the 2 wire-lead alt.version.
____ BTW, I've added some tid-bits of info which I had forgotten/neglected to include within my previous posts here, so you may care to read-through them again.


Hopeful-Cheers,
-Bob

[cgrace]

So...here are my readings. I dug out my factory flywheel puller in anticipation of your prognosis:

red to ground .3 closed
white to ground infinite /open
yellow to ground .6 closed
red to white infinite /open
white to yellow infinite /open
yellow to red 1.1 closed

[DewCatTea-Bob]

" So...here are my readings. "

____ I'll now begin adding my various comments to your findings, (this may take a while do to my current multi-tasking), so stay-tuned.
__ BTW, I consider it a bonus that your ohm-meter apparently conveniently measures below 1.0 ohms !


" red to ground .3 closed " - __ - That's pretty-much correct for the Lighting power-coil's alt.winding ! _ The Red wire-lead is connected to it's power-coil winding and the other end of that coil-winding is grounded (to the alt.stator).

" white to ground infinite /open " - __ - Since this White wire-lead doesn't have a circuit-path to ground, then it ought have a circuit-path to one of the other wire-leads ! _ If also not, then it must be broken.

" yellow to ground .6 closed " - __ - That reading seems to be correct for the alt.power-coil that's intended to power the ignition-system, and ought to run the ign.coil as it is.

" red to white infinite /open " - __ - As it should be. - (Since the R/T doesn't use any battery!)

" white to yellow infinite /open " - __ - Again, the White wire-lead ought to be connected to something.

" yellow to red 1.1 closed " - __ - This higher ohm-reading is to be expected because it indicates the resistance-total of BOTH alt.power-coils, (as your ohm-meter's test-current passes through one coil-winding, then into the stator-plate (which is 'Ground'), then from there into the other power-coil and back to your meter). _ However the difference between the stated "1.1" & the total of ".3" + ".6" is possibly due to a less than maximum connection with the meter's leads.

____ These results are indicative that your alternator is up-to performing it's jobs, however something is not right concerning the White wire-lead ! _ I think that a possible answer to this oddness is that it could be that sometime in the past, somebody replaced the original two wire-lead alt.cable with a 3 wire-lead version, and left the extra/(white) wire-lead unconnected. _ However that would've been a waste, as that wire could've then been connected-up along with the Red wire-lead and thus been made use of for another lighting-output.


" I dug out my factory flywheel puller in anticipation of your prognosis: "

____ Before you pull the alt.rotor (to have a look/see at what's-up with the White wire-lead) , you should hook-up the Yellow alt.wire-lead to the ign.coil, and check for ign.spark .
Is that possible for you to get done currently?
____ It's nice that you have a w-c alt.rotor-puller, since you'd need it in order to modify the alt.power-coil/stator connections, for running more street-legal lighting !


Tillater,
-Bob

[cgrace]

I can check for spark...but will have to wait until Thursday. Luckily I never sell old tools or manuals. You never know when you'll need them.

[cgrace]

No joy on getting any spark. I might have overlooked something but this isn't my first dance.

[DewCatTea-Bob]

" No joy on getting any spark. "

____ Double check that you have your ignition-wiring wired-up as stock...
The wire-lead from the points should be connected to either terminal-post on your ign.coil, and to that very-same post, so should be the Yellow alt.wire-lead connected, as well !
The other terminal-post on the ign.coil should be connected to Ground (usually by a short jumper-wire, from that second-post to one of the ign.coil-mount bolts.
__ If you also have a kill-switch wired-up, make sure it's not stuck On, (and that it's wire-lead is also connected to the same ign.coil terminal-post as the points & Yellow alt.wire-lead is).
__ You ought to get ign.spark when wired-up this way, (according to your stated ohm-meter readings which you obtained from/with your various alt.wire-leads), since your Yellow alt.wire-lead seems to be connected to the proper alt.power-coil (that's meant to power the ign.system), of which it's opposite coil-winding lead-end must already be grounded internally.
__ Please check it out again, and then get back to us with your latest results, before thinking about pulling your alt.rotor. - (Because the current rotor-timing should be recorded, before that info.data is lost !) _ As things should be, you ought to be getting spark.
__ Otherwise I'm starting to think that (since your White-lead is dead), maybe when somebody possibly replaced the alt.cable, they then possibly lost the original alt.rotor timing.


Hopeful-Cheers,
-Bob

[wcorey]

Could you hook it up directly to a battery, or does that not work on the R/T coil? Does it have to be ac?


Bill

[DewCatTea-Bob]

" Could you hook it up directly to a battery, "

____ Well Bill, you've somewhat jumped ahead with an idea I might've ended-up suggesting for Chris to try, (so as to determine if his lack of spark is solely due to lack of usable power from his alternator, or some other malfunction preventing spark-production).
__ To the specific question, it depends exactly what's meant by "it". ...
As normally wired-up, the answer is no, but it's possible to re-wire things so as to take the alt.power-source out of the picture and substitute battery-power, for the purpose of checking that everything else is good-to-go for spark-production.


" or does that not work on the R/T coil? "

____ I've found many old DUKEs with the Green ign.coil & Red ign.coil ign.system-parts all mixed-up in different ways,, some still running well enough & some running poorly if at all !!
I've never taken-apart the two different ign.coils to see exactly what their differences actually are but, I suspect that the Green-coil has less of a turns-ratio than the Red-coil has.
So while it's likely that the resulting ign.spark may not be as intended, a spark still results regardless of either ign.coil type being mated with either ign.system type.


" Does it have to be ac? "

____ While it's true that the 'power-source' for the Green-coil ign.system (as used on the R/T ign.system), is indeed 'AC' of course,, this type of ign.system's ign.coil is actually fired-off by DC (anyhow) ! ... Cuz while this ign.system's ign.coil is indeed exposed to AC power-juice so long as the points are open, (which is about 1/3 of the time, due to the shorter-duration of this system's associated cam-lobe), it's actually ONLY just one of the (either positive or negative) PULSES of 'DC' that's particularly needed to produce the ign.coil's spark ! _ (All the rest of the provided AC power-pulses [for the ign.circuit] are totally wasted!)


____ BTW Bill, what about the 4-pole alt.stator that was on YOUR 450R/T ? - Did it have any other wire-leads other than the two standard Red & White Alt.wire-leads ?
__ Also, have you ever checked to see if you have any 12-magnet alt.rotors that would properly fit over your R/T-stator ?


Dukaddy-DUKEs,
-Bob

[cgrace]

We have spark! Went back to basics, just to be sure. Retimed the engine, pulled the timing cover and reset the points with new point set and condenser, new plug wire. Used the yellow wire. Life is good.

[wcorey]

____ BTW Bill, what about the 4-pole alt.stator that was on YOUR 450R/T ? - Did it have any other wire-leads other than the two standard Red & White Alt.wire-leads ?

It did originally have just two somewhat stiff, cracked wires.

__ Also, have you ever checked to see if you have any 12-magnet alt.rotors that would properly fit over your R/T-stator ?

Here we go spreading this topic around to yet another thread, lol.

No, none of the Denso rotors I have are the correct diameter to work with the (unmodified) two coil R/T stator. I had initially planned to make an adapted mounting plate to add a third coil to try on both the Ducati 6 pole rotor and a 12 pole Denso but when I started playing with the Denso stators that idea fell by the wayside. That and when I had no success using the 4 coil n-c stator with the 12 magnet rotors, I was concerned that the 3 coil adaption mightn't work either so didn't want to waste effort better applied elsewhere.

In an attempt to rearrange magnets for 'alternative results', I dissected an older type Denso 12 magnet rotor and found that the three (continuous looking) sections that can be seen around the inner perimeter are the actual magnets, not just covering material. While each (solid and physically undivided) section is comprised of 4 magnetic poles, oddly they aren't equally positioned. Each segment has only 3 complete poles, not necessarily centered, with the remaining 4th pole in unequal parts on either end. One segment may have a third of a pole at one end and the next segment has the other two thirds and continues as such onto the next one. Not sure of the manufacturing process but it seems like they must first be assembled and then magnetized afterward. If such is the case then it should be possible to de-magnetize the whole thing and redo it to function with a different stator configuration. Unfortunately not something I'm set up for...

Bill