Could the rotor go bad because of the way the PO did things? That gets a good solid maybe for an answer.
The rotor goes bad from excessive heat build up over a long period of time. What the PO did probably wasn't run that way long. A few years maybe.
The regulator turn the power through the rotor on/off as needed to keep the battery at full charge. It cycles the rotor on/off thousands of time a minute.
With a good battery the on time is much less than the off time. The rotor can coolff some when in the off time. When the battery gets weak the on times increases. If the battery is weak enough the on time may be 100% instead of like 25% with a good battery, just a guess on that.
Anyway with the rotor on all the time it doesn't have much time to cool off. THe heat builds up, enough so the insulation on the wire in the windings starts to melt and burn. This discolors the coating used to seal and protect the windings. A new rotor the windings will have a nearly clear slightly yellow color. As the heat works on it it gets darker and can look black.
Once the insulation burns the wires can touch. This reduces the ohms. Less ohms means higher current flow. More current makes more heat. A visious circle. Eventually the rotor gets so bad it can't do it's job.
Yours at 2.4 isn't totally shot but very close. With every thing else good that rotor may at best break even. On my 81 the rotor read 1.5 ohms. It would charge just enough to turn the headlight on and run the bike awhile but after a short time the extra draw of thinmbgs like brake light, turn signals and such the battery would go dead. Recharge the battery and ride it a few more hours.
Not a good way to do things.There are places that rewind rotors. Call Gary at Custom Rewinds, darn I can't find the number. Google Custom Rewinds. The number is on the web site. Many have had great results with rewinds from there. I think the last time I checked the price was $125 or $150 plus shipping. If he has the puller when you call you can borrow it to pull t your rotor. Use the proper tool. Most anything else can damage the rotor. A damaged rotor can't be fixed.
When you test the voltage at brushes you need to check the battery voltage under the same conditions as when you test the brown wire. If you check battery voltage with the key off it will read higher than when the key is on. The draw from the ignition, any lights and such will lower the battery voltage. When you check battery voltage, key ofv it might read 13.2, turn the key on and it might read 12.7. Compare the brush voltage to the 12.7.
I might suggest for trsting hook up a bigger battery. That tiny 1.5 amp battery won't stay charged long enough to test much.
Have you tested the ohms on the stator wires? With the yellow wire unhooked, test the 3 whites from wire to wire as well as wires to ground.The exact ohms isn't as important as they all match. Some specs call for .9 ohms, others call for .46. As long as they all match and no continuity to ground the stator is fine.
On your meters try the leads from the new one on the old one. Bad leads cause worlds of trouble.
Leo
The rotor goes bad from excessive heat build up over a long period of time. What the PO did probably wasn't run that way long. A few years maybe.
The regulator turn the power through the rotor on/off as needed to keep the battery at full charge. It cycles the rotor on/off thousands of time a minute.
With a good battery the on time is much less than the off time. The rotor can coolff some when in the off time. When the battery gets weak the on times increases. If the battery is weak enough the on time may be 100% instead of like 25% with a good battery, just a guess on that.
Anyway with the rotor on all the time it doesn't have much time to cool off. THe heat builds up, enough so the insulation on the wire in the windings starts to melt and burn. This discolors the coating used to seal and protect the windings. A new rotor the windings will have a nearly clear slightly yellow color. As the heat works on it it gets darker and can look black.
Once the insulation burns the wires can touch. This reduces the ohms. Less ohms means higher current flow. More current makes more heat. A visious circle. Eventually the rotor gets so bad it can't do it's job.
Yours at 2.4 isn't totally shot but very close. With every thing else good that rotor may at best break even. On my 81 the rotor read 1.5 ohms. It would charge just enough to turn the headlight on and run the bike awhile but after a short time the extra draw of thinmbgs like brake light, turn signals and such the battery would go dead. Recharge the battery and ride it a few more hours.
Not a good way to do things.There are places that rewind rotors. Call Gary at Custom Rewinds, darn I can't find the number. Google Custom Rewinds. The number is on the web site. Many have had great results with rewinds from there. I think the last time I checked the price was $125 or $150 plus shipping. If he has the puller when you call you can borrow it to pull t your rotor. Use the proper tool. Most anything else can damage the rotor. A damaged rotor can't be fixed.
When you test the voltage at brushes you need to check the battery voltage under the same conditions as when you test the brown wire. If you check battery voltage with the key off it will read higher than when the key is on. The draw from the ignition, any lights and such will lower the battery voltage. When you check battery voltage, key ofv it might read 13.2, turn the key on and it might read 12.7. Compare the brush voltage to the 12.7.
I might suggest for trsting hook up a bigger battery. That tiny 1.5 amp battery won't stay charged long enough to test much.
Have you tested the ohms on the stator wires? With the yellow wire unhooked, test the 3 whites from wire to wire as well as wires to ground.The exact ohms isn't as important as they all match. Some specs call for .9 ohms, others call for .46. As long as they all match and no continuity to ground the stator is fine.
On your meters try the leads from the new one on the old one. Bad leads cause worlds of trouble.
Leo
