Testing a generator rotor

[Fencingboy]

I've been trying to resolve my 79 750L not charging for a while now and I've concluded that everything is good except for the generator rotor. according to cb750c.com, a basic test for a rotor is to measure resistance between the two slip rings and that it should be between 3.6-5.2ohm. Other forum posts say that the usual failure mode for a rotor is an internal short between the two slip rings, causing them to have less resistance than specified. On both my original rotor, and a replacement rotor I bought from rick's motorsport electric, there is no continuity at all between the two slip rings.

THE QUESTION AT HAND: Am I doing this right? Just because my finding for both of the rotors is the opposite of what seems to be the usual failure mode, I'm questioning that I'm testing it correctly. RME has said if I mail the parts to them, they'll do their own tests and issue replacements if the part to them, so I'm most likely going to be doing that.

Thank you to the kind people of this forum

 

[Connella08]

here is a fantastic video showing a BRAND NEW Honda rotor being tested.

standard procedure for proper multimeter use is that you want to test the meter first to confirm that it works, then test your work piece, then test the meter again. this is because you don't know if the meter stops working during your test. naturally, you can conclude that if the meter worked before and after the test, that your test must be conclusive. if you touch your leads together, you should hear a beep. if you touch the leads to the rotor, you might hear a beep but you should also see a resistance value. if you don't get either, then you likely have a broken wire inside of the rotor.

 

[Fencingboy]

here is a fantastic video showing a BRAND NEW Honda rotor being tested.

standard procedure for proper multimeter use is that you want to test the meter first to confirm that it works, then test your work piece, then test the meter again. this is because you don't know if the meter stops working during your test. naturally, you can conclude that if the meter worked before and after the test, that your test must be conclusive. if you touch your leads together, you should hear a beep. if you touch the leads to the rotor, you might hear a beep but you should also see a resistance value. if you don't get either, then you likely have a broken wire inside of the rotor.

Thank you! exactly the resource I needed. Rotor is going back to RME, who should be sending me a replacement shortly.