Only one generator wire producing voltage and current

[mrkprsn]

George,

That pic is exactly what I am looking for. That definitely helps. My stator is the same one wired the same way. Now I know the stator was wired correctly and that is what came on my 200GT.

What rectifier did you have? Was your original system 28 watt or 40 watts? Did you have a regulator? Is there a wiring diagram for your Elite? That info made my day! Sorry for all the questions.

Thanks, Mark

[mrkprsn]

Graeme,

I believe that the stator mounts using the same 3 screws. I will find out.

Jordan,

I tested the alternator by connecting it to an analog voltmeter while the bike was running, I put it inline between each alternator wire and the RR.

I connected each stator's wire to the pos+ terminal of the meters and connected the neg - terminal of the meters to the RR where the stator wire would go. I did the same thing with an analog ammeter to test the current. One wire produced 7V6A and the other wire produced nothing.

I also did a resistance check and both stator wires tested out to be around .2-.3 Ohms each. I would like to know how to bench test that stator's coils to see if they are OK.

Cheers, Mark

[Ventodue]

Thanks Dave. Do you have a parts book that shows the 40watt alternator (0400.33.xxx) fitted to a 250 Monza or GT?

FWIW, this is 1961 (and April 1963 is the same) for 250 Monza and Diana.
6v-40W. Part no. 0400.33.410.

250 Monza.jpg

(The 200 Elite manual that I have from 1960 uses the previous parts numbering system. EG4421.4002. Again 6v-40W.)

<snip> I've never seen a wiring diagram for the 200GT, just the 250GT ...

I have one for the 200 Super Sport and Turimo Sport (February 1959), if you think that might be of interest.

[Jon Pegler]

Part number EG4421.4002 is 0200.33.400 in the later numbering scheme.

Jon

[George]

George,

That pic is exactly what I am looking for. That definitely helps. My stator is the same one wired the same way. Now I know the stator was wired correctly and that is what came on my 200GT.

What rectifier did you have? Was your original system 28 watt or 40 watts? Did you have a regulator? Is there a wiring diagram for your Elite? That info made my day! Sorry for all the questions.

Thanks, Mark

Hi Mark
I am no expert with electrics. The Elite manual states 40 Watt, The wiring diagram shows 3 wire stator. The rectifier was the old original with large cooling fins. I believe that Ducati did not fit regulator but wiring was such that when you turned lights on 2nd coil kicked in. when off 1 coil fed ignition. Of course being over 55 years old any of this could have been changed by previous owners. I never run engine with Ducati alternator and cannot give any details. I could see no point on relying on 55 year old rectifiers, wiring, insulation etc etc. that is why I fitted Electrex system.
Let me know If there is anything you want me to check on my stator, or make me an offer for complete alternator remember wire will need replacing as insulation poor.

[Jordan]

I connected each stator's wire to the pos+ terminal of the meters and connected the neg - terminal of the meters to the RR where the stator wire would go. I did the same thing with an analog ammeter to test the current.

May I suggest you alter the connection points for coil voltage tests?
Set multi meter to AC voltage, range about 100V. Or, use your dedicated AC voltmeter.
Select one coil. Connect a meter probe to the end of one of the 2 wires, disconnected from the rec/reg. Connect the other probe to ground. Run the engine up to around 3000 rpm and take a reading.
Do the same with the other coil.
Do not involve the rec/reg for these tests. You just want to know how much voltage the coils make, unregulated.
I'm wildly guessing you could get 20 to 50 volts from each coil.
Just for fun (data), test for the voltage output between the 2 wires as well.
At this stage I don't think a current test is very useful, because you are not connected to any load.

[mrkprsn]

Jordan,

I already have the old stator out of the bike and there are no replacement rectifiers for the Elite. I am also not convinced that there is not a short somewhere in it. I also installed a new wiring harness that is wired for the standard 250's battery system and I have a new RR from Lacey as well as the older 6 wire Ducati black box RRs.

I am going to try to mount the 60 watt stator and flywheel that came on the 250s. If that doesn't work then I will fall back to reinstalling the old stator and try to find a 3rd party rectifier that will work.

The next time I test the alternator I will do it as you suggested and not ground it to the RR. I did do a voltage test between the 2 stator AC wires and got 30-35V. The current test actually does work because it flows through the ammeter to the RR and then onto the lights, ign coil, etc. So there is a load. Next time I will ground it to the frame and compare the results.

Thanks for your help, Mark

[mrkprsn]

George,

In my both my parts books (Elite & 200GT) the illustration shows a 3 wire stator, but as you can see the stator (yours and mine) had only two wires. Thank you for the offer of buying your stator and flywheel. I already wired it like a typical 250 battery system so I am going to try to upgrade to the 60watt 250 battery system. Interestingly there was another RR that Ducati used on the 200s. I've never seem one. It seems like the used this between the Elite rec only system and the 60 watt 250 system. Below is a pic. Thanks, Mark

PXL_20231011_141858857.jpg

PXL_20231011_142007252.jpg

[George]

George,

In my both my parts books (Elite & 200GT) the illustration shows a 3 wire stator, but as you can see the stator (yours and mine) had only two wires. Thank you for the offer of buying your stator and flywheel. I already wired it like a typical 250 battery system so I am going to try to upgrade to the 60watt 250 battery system. Interestingly there was another RR that Ducati used on the 200s. I've never seem one. It seems like the used this between the Elite rec only system and the 60 watt 250 system. Below is a pic. Thanks, Mark

PXL_20231011_141858857.jpg

PXL_20231011_142007252.jpg

Hi
Couple of years since I altered Elite wiring but if memory services me well I recollect that rectifier outputs one went to ignition switch to feed ignition and one went to light switch and went live when turning lights on and connecting to one of the stator wires with wire feeding battery somewhere in the circuits? I might be wrong.
Attached link is a good article on testing and understanding motorcycle charging systems. Wrote for 12v system but basics are the same just alter some readings. I printed off a copy and refer to it regularly https://www.aberdeenbikers.co.uk/motorc ... is-checks/

[mrkprsn]

George,

Well just when I thought things couldn't get worse, they did. The 60 watt flywheel will not fit and the 40 watt flywheel will not fit over the 60 watt stator. Ugh. It looks like I am going to have to make the old stator/flywheel combo work. Unfortunately there is no direct replacement for the rectifier and the old ones are non existent. I may take you up on buying your stator if I can't fix mine.

Thanks, Mark