Charging issue

I am having a charging issue, bike runs. At 2,000 RPM I am only getting 13.5 volts at the battery. Checked the brushes, stator and rotor. Brushes are good well above the scribe lines. Test the stator resistance on the white wires all with in the 0.5 ohms. Tested the rotor and here is the issue. Checked resistance on the green and brown wires resistance bounced around but always above 4.5. Took the alternator cover off test the resistance on the rotor it self and it bounced around from 5 to 30. I just need another opinon. Make sure i checked everything. Can you fix the rotor?

Sorry for it being so long

 

Rotors are rebuildable but the cost to have it rewound is great enough that it makes more sense to simply purchase a new unit. I believe new rotors can be had for about $180. Chacal, want to chime in?

 

would a rotor from a 82 750 max work in my 83 550? ound one just dont know i it will it?

 

please someone let me know.

 

Nope. 550's are unique. I am assuming you probably have a 550 Maxim? Checking part numbers, I discovered something interesting: 1981, 82 and '83 Maxim 550 and '81/82 Seca 550 have the same alternator but the '83 Seca has a completely different part number. Look at my bike list you'll see why I find this worthy of note...

 

I have another quick question. It you unplug the stator and the 3 white wore connection under the seat. What ac voltage should you have? My brushes are under 11mm but above the scribe lines. Should I replace them? Please I need some guru help.

 

Tubs, you should be very careful when you measure the A/C output of the alternator rotor. If you don't disconnect the ignition system, you will fry things. You can assume that you should see about 18-19 volts A/C per phase (14 V RMS is the rectified output so just add 30% to that, its a good rough measure). As for the brushes, replace them and eliminate all doubt. Its cheap enough (about $15 a set).

 

the recommended replacement measurement I believe is 10mm so to me your 11 is close enough to reason to replace them before you drive yourself crazy when it could be as simple as the brushes.