dirtbiketimmy
CB750 New member
Hello,
First post to this site but I've used it extensively as a guide so thank you all. I can normally figure things out using the search and finding existing information, but I'm really stuck here. It seems there are others with charging issues lately, but unfortunately none of their problems have helped me find mine.
First of all, the bike is a 1975 cb750k. The problem I'm having is that the battery is not being charged while the bike is running. The battery takes and holds a charge (12-13v) from a battery charger and is less than two years old. The starter solenoid was recently replaced, as it was bad and somehow stopped the rest of the bike from getting any power. Fuses are good. Recently replaced the rectifier. Checked the voltage regulator and its clean (tried adjusting it, which did not change anything). I did remove the starter motor because it did not work so it's kick start only.
I did a resistance test of the alternator as per the shop manual and everything checked out, 7ish ohms on the field coil (between white and green) and roughly .2 ohms the stator coils (yellow wires).
I'm getting 13-16 DC volts depending on rpms when i measure across the red and green coming from the rectifier. This leads me to believe that the alternator is producing voltage and it is being converted to DC. However, when i measure voltage at the battery, it does not increase with revs. I also did the current test, where I put my meter in series with the batter and it showed -1 when running and -7 with the lights on. This shows me that the current is only leaving the battery, and not going to the battery like it should be.
Additionally, I am getting a nasty clanky sound coming from the alternator area on the engine. It sounds almost like there is something loose bouncing around in there. I will open that up and check it out, but since I'm getting voltage form the alternator it doesn't seem like that is the issue.
I think I've attached a photo of the red and green wires from the rectifier that show 13-16 volts (increasing with revs)
If anyone has any ideas I'd really appreciate any feedback. I've tried everything I know of. Thanks in advance.
First post to this site but I've used it extensively as a guide so thank you all. I can normally figure things out using the search and finding existing information, but I'm really stuck here. It seems there are others with charging issues lately, but unfortunately none of their problems have helped me find mine.
First of all, the bike is a 1975 cb750k. The problem I'm having is that the battery is not being charged while the bike is running. The battery takes and holds a charge (12-13v) from a battery charger and is less than two years old. The starter solenoid was recently replaced, as it was bad and somehow stopped the rest of the bike from getting any power. Fuses are good. Recently replaced the rectifier. Checked the voltage regulator and its clean (tried adjusting it, which did not change anything). I did remove the starter motor because it did not work so it's kick start only.
I did a resistance test of the alternator as per the shop manual and everything checked out, 7ish ohms on the field coil (between white and green) and roughly .2 ohms the stator coils (yellow wires).
I'm getting 13-16 DC volts depending on rpms when i measure across the red and green coming from the rectifier. This leads me to believe that the alternator is producing voltage and it is being converted to DC. However, when i measure voltage at the battery, it does not increase with revs. I also did the current test, where I put my meter in series with the batter and it showed -1 when running and -7 with the lights on. This shows me that the current is only leaving the battery, and not going to the battery like it should be.
Additionally, I am getting a nasty clanky sound coming from the alternator area on the engine. It sounds almost like there is something loose bouncing around in there. I will open that up and check it out, but since I'm getting voltage form the alternator it doesn't seem like that is the issue.
I think I've attached a photo of the red and green wires from the rectifier that show 13-16 volts (increasing with revs)
If anyone has any ideas I'd really appreciate any feedback. I've tried everything I know of. Thanks in advance.
