Alternator stator.

[Haggis]

I have been inspecting various bits and pieces prior to a major rebuild. - I have had this bike in a box for about 25 years and reckoned it was about time to either rebuild it or pass it on.

The alternator stator is in a bit of a bad way. It looks as though the original cause of the bike being laid up might be the melted green wire in the picture. Although the broken kick-start boss in my previous message would not have helped. (possibly the two are connected. I have a vision of the previous owner kicking the engine furiously as the alternator shorts out)

The yellow cables are hard and cracked and will obviously need to be replaced. Can I use suitably sized two core or is there a particular specification I should look for given that the wire will be subject to heat and vibration in the casings. Any suggestions or sources for the wire would be appreciated. I am in the UK, but presumably could get it posted from US if necessary.

Thanks

Chris.

[graeme]

Hi Chris,
I used rubber insulated 3 core and have had no problems.
On supermarket freezer glass doors this is used to connect the door heater, it is rated -40 to 120 degrees C.
The original cable seems to be rubber insulated. There would be better stuff like Teflon insulation that is more suitable to being boiled in oil but I couldn't easily find any.
Graeme

[DewCatTea-Bob]

" The alternator stator is in a bit of a bad way. It looks as though the original cause of the bike being laid up might be the melted green wire in the picture. "
The yellow cables are hard and cracked and will obviously need to be replaced. "

____ I gather that your presented stator is from a 4-speed 'Diana 250' or '250 Monza', correct ?
In ANY case, I'm sure it's not as factory-stock, due to the added green-wire (of which seems to be a [fairly smart] modification done by someone-else).
To confirm that your alt.stator has indeed been so modified,, look it over closely for any signs of where that lead-end (that's now seen connected to the green-wire), may have originally been soldered directly-to (someplace on) the stator-plate.
(A better pic.shot of the stator's connection-board area may be of use, so as to better discern exactly what's-what with your stator.)


Hopeful-Cheers,
-Bob

[Haggis]

Thanks Graeme I will ask around and see if I can get hold of some of the cable you suggest. That was a good bit of lateral thinking on your behalf. If the third wire turns out to be a useful mod, three core might be a good solution.

In response to Dew-Cat-Tea bob:

As far as I am aware the bike is a 4 speed 250 Daytona (Diana in America I believe) probably a 1962 model- but I need to check further. It has clip ons and smooth top triple clamp. I am not sure that these are original. The photo shows a dry assembly with Italian frame and Spanish forks / seat / engine. (The paintwork was done by a friend who was a little creative in his interpretation of the pictures I gave him. - what can you say?)

I presumed that the green wire was a replacement for the original as it passes through a woven sleeve and appears to go to earth, (see photo). However I will happily take your word that it is a mod. Would this be to improve the earthing of the entire system? Looking at the gauge I suspect it is a case of good intention with the wrong piece of wire. At the moment I am stripping and cleaning bits, but I suspect some testing will be a good idea before reassembly. I will do some research, but I am sure there will be a few questions about the electrics to come.

Regards

Chris

[DewCatTea-Bob]

" the bike is a 4 speed 250 Daytona (Diana in America I believe) probably a 1962 model- "

____ And the alt.stator you've pictured is the stock-model for your Duke-model which has the dual half-wave charging-system.
__ Does your Duke still retain the original-type black-box power-regulator ?


" I presumed that the green wire was a replacement for the original as it passes through a woven sleeve and appears to go to earth, "

____ I've never seen a stock alt.stator with two yellow wire-leads along-with a third/green wire-lead. _ The stock alt.stator-cable should only contain just the two yellow-wires within it's black-conduit/covering... Your alt.stator's original/stock cable-conduit could-not have been modded with the additional/green-wire inserted-through along-with the pair of yellow-wires.
And since your YELLOW-wires are suffering from the common-issue of disintegrating-insulation, then THOSE two wires are no-doubt original,, and-so thus the green wire must've been a mod.add-on. _ So that third/green-wire must've been separately routed from the pair of yellow-wires, correct ?


" However I will happily take your word that it is a mod. "

____ Yes, and it's a mod that may've been done by someone who knew of my very-own recommendations for modifying the charging-system. _ But considering your location, it's also believable that someone-else also logically came-up with the same sensible-reasoning for that particular modification, as it all stands to good-reason.


" Would this be to improve the earthing of the entire system? "

____ Well it could possibly help but, it's not too likely that it would make any real significant difference as to the earth-grounding of the alt.stator-windings' grounded ends.
The purpose of using the added green-wire, is to move-out the original/internally grounded-connection so that it's relocated to an external-location where it can then be much easier to work with (for various charging-system modifications).
__ Do you wish to stay original with your Duke's electrical-system ?


Duke-Cheers,
-Bob

[Haggis]

Bob.

I missed a couple of your points in my answer.

I am not sure whether I have the original rec / reg box. I have an old Mk III W/C unit, but I don't think it came with the bike.

It is unlikely that I will keep the original system. There seem to be some good replacements as well as the odd higher capacity original units available. At the moment I am considering all of the potential mods and weighing up the original v. more reliable or robust options.

Thanks

Chris.

[DewCatTea-Bob]

" I am not sure whether I have the original rec / reg box. "

____ It's black (with some gray) & heavy, and has six terminal-connections.


" I have an old Mk III W/C unit, but I don't think it came with the bike. "

Since your stator has been modified (with the added green-wire), I'm now thinking that that stator-mod was done so that it can be used to work-together with a w-c.type reg/rect.unit, and-so the w-c.r/r.unit you have quite possibly did indeed come "with the bike", (although not original-stock to your older Duke-model).


" It is unlikely that I will keep the original system. "

____ I don't (so far) see why not,, as whether you have the original n-c.type or choose to make-use of your w-c.type r/r.unit, your currently-existing alternator/charging-system should quite adequately serve a near stock load-system.


" There seem to be some good replacements as well as the odd higher capacity original units available. "

____ By: "the odd higher capacity original units" , I assume you're probably meaning to be in reference to the '6-pole' (4 dual power-coil) alternator-model which came-stock on the newest n-c.models,, correct ?
__ While the 6-pole alt.model was 'rated' at "60- watts" and your 4-pole alt.model had been 'rated' at only "40 watts", I can only confirm that the updated/6-pole alt.model operates at a 50% higher frequency, (but not that it actually does indeed also provide 50% more power).
Also, in favor of the 4-pole type alternator,, the higher-frequency a single-phase type alternator provides it's AC.output, the more-difficult it becomes to start-up the engine (and keep it running at low-RPM) without a charged battery.


" At the moment I am considering all of the potential mods and weighing up the original v. more reliable or robust options. "

____ Such as / what-all are you most strongly (at this time) considering ?


Duke-Cheers,
-Bob

[Haggis]

I originally thought I would get all of the bits of the bike together, see what I had and work from there. It did not work out like that as I started asking questions about the alternator, took the crank to be split etc.. So I still need to go through all of the bits and pieces to see what I have. It may be that I have the original reg / rec.

It seems that with a bit of patience most bits can be found on ebay or other sites on the internet, so I was thinking that if the crank taper is repairable I would either find a replacement original rotor that has not been spun (unlikely, going by some of the threads on the forum) or buy a complete new charging system such as the one from Classic Ducati at http://www.classicducati.com/index.php?act=viewProd&productId=217.

I am just looking around to see what is available while planning the rebuild. Any advice is welcome. Keeping the bike original is one of my main priorities, but getting out on it and having fun is another. I had not thought about your point that:

"Also, in favor of the 4-pole type alternator,, the higher-frequency a single-phase type alternator provides it's AC.output, the more-difficult it becomes to start-up the engine (and keep it running at low-RPM) without a charged battery. "

Having had Ducatis as my main form of my only form of transport in the 1980's I am aware that keeping a good one on the road can be challenging,so I was planning to eliminate as many sources of grief as possible by using good practice and good parts. At the moment this is all background research while I am replacing bearings and seals and sorting out the crank.

Thanks for the invaluable advice. It is much appreciated.

Chris.

[DewCatTea-Bob]

" It may be that I have the original reg / rec. "

____ Since you have a w-c.type r/r.unit, it can work with your alt.stator modified as it has been.
That update-mod was a somewhat common & approved modification, so if you got the w-c.r/r.unit with your basket-case, then that's probably what had been intended (even though someone added a green-wire* instead of a red one).
(* I-myself used to tell others to add a "green" wire but, not specifically for adapting a w-c.r/r.unit.)


" so I was thinking that if the crank taper is repairable I would either find a replacement original rotor that has not been spun "

____ Cranks & rotors that have come-loose and been spun together usually don't REQUIRE to be 'repaired' (unless unusually severe), simply torquing them back-down together quite-well usually sticks them back-together at least as strongly as the original smooth/flat surfaces had once been. - (It actually depends on how the wear-lines happen to end-up lining-up together, as it could possibly happen to line-up in such a way as to be LESS strongly adhered,, although chances are against such poor-luck, [unless a rotor had not been 'spun' on the same shaft, of-course].)


" or buy a complete new charging system such as the one from Classic Ducati "

____ I absolutely deplore such advertizing that promotes such put-down of Ducati-made parts so as to scare Duke-owners into believing that they need to replace the original-parts with THEIR 'new & improved' -(expensive) upgrades.
I feel that going that route is just a step towards replacing the entire motor with a 'upgraded' one. - It's just not REAL 'Ducati' anymore, then !
If you'd consider installing an aftermarket charging-system, then why not just go-ahead and put a XL250 Honda-motor (or the like) into your "bike" !?
(I-myself prefer MY DUKEs to be nearer 100% Ducati !)


" I had not thought about your point that:

Also, in favor of the 4-pole type alternator,, the higher-frequency a single-phase type alternator provides it's AC.output, the more-difficult it becomes to start-up the engine (and keep it running at low-RPM) without a charged battery.

"
____ While it doesn't matter much when a high-frequency alternator is a 3-phase type, single-phase high-frequency alternators produce power-pulses that are too short in duration* to properly saturate the ign.coil. _ While the 4-pole easily provides enough saturation-juice to produce an ign.spark at kicking-speed (without a charged battery needed to help-out).
(* The duration of a power-pulse from a 12-pole alternator is only 30-degrees [of crank-rotation] long, where-as the 4-pole lasts 90-degrees. _ So that's an important consideration, when the auto-advance spans 28-degrees, and only most of the up-ramp side of the power-pulse provides the required coil-saturation, [thus cutting the time-length roughly in-half (down-to about 15, or, the original 45 degrees)].)


" so I was planning to eliminate as many sources of grief as possible "

____ I don't see the stock charging-system as being any 'source of grief' .
Only those who wish to sell you replacement-parts will 'promote' such thinking.
The stock system is quite adequate, unless you intend considerably greater system-loading.
__ How much power do you expect for your intended headlight to draw ?


Duke-Cheers,
-Bob

[Haggis]

Thanks Bob.

Here is a picture I put on another post. As you can see the taper is well and truly spun. The eng. shop which is splitting the crank is going to try spiral welding it and then regrinding. The problem I have is that the rotor is just as bad, so it seemed pointless to put it on a repaired shaft, That was why I was considering my options. At the moment I am concentrating on getting the engine built. - new bearings and seals all round. The rest of the build will no doubt raise lots of questions and I will be gratefully seeking your advice.

Do you know why there is no woodruff key on the tapered shaft? I was guessing that it would be a stress point and may cause the shaft to fracture. The guy in the eng. shop was surprised that the alternator relies simply on the friction of the taper.

Thanks

Chris.