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My 200GT has the "B" 250 engine with the 200 barrel. It was registered as a 1966 but was supposedly made between 62-63 but maybe not. On the wiring diagram Ventodue posted, there is a Westinghouse 10a rectifier. We know there is also a Westinghouse 20a rectifier for the Elite and the 60 watt black box RR for the 250's. There is also a 40 watt black box RR for the 200GT. Has anyone every seen one of these. I wonder is this is what I need.


I tested my stator for continuity. There was continuity among the two wires, all the solder points and the metal ends (where the screws mount the coils to the plate) of the coil without the wires. There was no continuity to the ends of the other coil (with the wires).

By attaching the coil without the wires to the plate you automatically ground it unless you put a layer of insulation between the coil and the plate. That would raise the coil up at a different height than the other coil. It might also interfere with the flywheel.

For fun, if anyone has this same coil, could you do the same continuity tests I did? I'm interested to know if the end of both coils show continuity or if just the coil without the wires. I hope this make sense.

George, Can you test your stator for me? Thanks, Mark

I will check it out tonight. I might be wrong and I am sure more knowledgeable members will correct me, I seem to recollect that one of the coils had double windings to give more output

mrkprsn wrote:My 200GT has the "B" 250 engine with the 200 barrel. It was registered as a 1966 but was supposedly made between 62-63 but maybe not. On the wiring diagram Ventodue posted, there is a Westinghouse 10a rectifier. We know there is also a Westinghouse 20a rectifier for the Elite and the 60 watt black box RR for the 250's. There is also a 40 watt black box RR for the 200GT. Has anyone every seen one of these. I wonder is this is what I need.
PXL_20231011_141858857.jpg

I tested my stator for continuity. There was continuity among the two wires, all the solder points and the metal ends (where the screws mount the coils to the plate) of the coil without the wires. There was no continuity to the ends of the other coil (with the wires).

By attaching the coil without the wires to the plate you automatically ground it unless you put a layer of insulation between the coil and the plate. That would raise the coil up at a different height that the other coil. It might also interfere with the flywheel.

For fun, if anyone has this same coil, could you do the same continuity tests I did? I'm interested to know if the end of both coils show continuity or if just the coil without the wires. I hope this make sense.

George, Can you test your stator for me? Thanks, Mark

Hi Mark
I have read again this thread from the beginning and would like to make some comments without meaning offence.
1) You have not said what electrical issues you were having.
2) You say that you have rewired almost everything, did you make notes or take photos of anything done different.
3) I get the feeling that you are getting things complicated, maybe try to get back to basics, one thing at a time.

With regards to coils resistance you do not say what figures you obtained. You state that both wires go to one coil I believe that is not correct, the two wires are outputs and connect to both coils with one coil being double windings (remember coil wires are shellac insulated.)
Image attached of my test. Multimeter set on 200 ohms probes touched together to give probe wires resistance mine was 0.2 ohms. Probes on coils wire terminals this gives resistance for both coils. mine was 0.7 minus 0.2 = 0.5 ohms this is within limits. this test is checking coils wire insulation.
Good luck, hope you are not going to spend to much with no good results, electrix 12v alternator is £300

Hi George,

The issues are that I was getting 7v6a at from one stator wire and nothing from the other. I did the test inline to both a black box RR and a new RR I just got from Lacy. I may have done the test incorrectly. Next time I'll do the test to ground instead of the RR as recommended by Jordan. I had old stator wires that had to be replace anyway so I decided to see why one wire wasn't producing anything.

The old wiring harness was a mess and disintegrating. I rewired the bike to the 250GT spec. That part works fine. A this point I 'm just trying to see if there is anything wrong with the stator. That's why I'm curious about the continuity test. I can't seem to figure out how to "unground" this stator if I have to.

The two wires go to the same coil but one wire seems to be the actual winding and the other wire seems to go through the coil. It's also wire slightly differently than yours. If you look my outside wire goes the the closer coil and your outside wire goes to the farther one.

I have the same resistance numbers you have. Do you have continuity to the ends of the coil that the wires go to? Do you have continuity to the end of the other coil?

My plan is to put everything back and retest and see if changing the wires had any effect. Thanks for your help, Mark

A good plan.
If it does not work out and you are in the UK I don't mind posting my complete alternator to you to give it a try