QuestionHello i recently acquired a 1971 honda cb350. i cleaned the carbs, cleaned the plugs, drained the tanks, basically got it to start. the bike hasn't been run in 5 years but i was able to get it going. however I'm having a problem with the charging system, it just wont charge. I'm trying to figure out what the 4 wires coming from the alternator should have for signals, IE voltage or AC/DC. I already know which wire is the neutral switch, green and red, but i can't figure out what the other 3 are.
AnswerMike... Here is a wiring diagram for reference...
http://oldmanhonda.com/MC/WiringDiagrams/MCwiring.php
The three wires are all carrying AC voltage to the rectifier (well two do directly). The third one will be added in when the headlight ON is selected. There is a current regulator, bolted to the bottom of the battery box.
In many cases, the rectifier gets damaged from people running the engine with a dead/dying battery.
Test the diodes in both polarities with an ohm meter. You should have current flowing in only one direction.
You can do a quick check of the stator output with a 12v test light, but only at idle. The Pink wire will have double the voltage (and brightness) of the other two. If you rev it up with the 12v light attached, it will blow up/burn out, as the system will generate about 40 volts AC when the engine is going over a couple thousand rpms.
You can use an AC voltage meter and check outputs at each wire, as well.
Make sure that the battery is fully charged. The system is designed to maintain a fully charged battery, but won't do much to charge up a low-charged battery.
Bill Silver
