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Honda CB750K5 Restoration by Royhall
royhall:
--- Quote from: Bryanj on October 03, 2023, 05:31:14 PM ---Check that the green wire from field coil goes to earth then temporarily connect white to battery positive then disconnected yellow wires should give the ac volts between wires THERE IS NO CONNECTION TO GROUND on this system.
If you dont get ac volts chances are the connectors at generator are bad
--- End quote ---
Cheers Bryan. I will try that tomorrow when it's reassembled. Green wire checks okay to earth.
BigAl (Alan):
Not sure if your meter reads DC amps? If so, you can connect a + fused lead from the meter to your battery + terminal (battery must be fully charged)
Then remove the white flag terminal from the regulator and fit to the common terminal on the meter (image attached)
Run the engine, the field coil will be fully excited, your meter may read 1.6amps (assuming a 7.5ohm field coil is fitted)
If no reading there could be a coil winding or earthing issue.
royhall:
Thanks for that Alan. Had to read it three times but I think I understand that. Basically your connecting battery live through the meter in series to field coil (on) (white wire) and taking the reading. I think my meter is capable of connecting 20 amp circuit. Will have a go tomorrow. Got to put it all back together first. Thanks.
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royhall:
I have had the the side castings back off the engine to check the alternator and the connections, and to check nothing got trapped. All looked correct and tested correctly and is now reassembled. So I then hooked up the meter as Alan suggested to read the current to the field coil (coil previously tested at 7.4 ohms) leads running through the meter connected from battery to disconnected white wire at the rec/reg. My second meter was connected across the battery set to volts DC. The static voltage on the battery read 12.81 volts, on starting the engine battery voltage jumped to 13.90 volts (revving the engine got it just to 14 volts) and the current on the white wire read 1.69 amps.
That proves the charging system is working fine. What happened here was a classic case of too little working knowledge of the system. Previously if I was changing something like a rec/reg they come with instructions about what plugs where and that's all I did. There had been nothing wrong with the system all along, but very much not a waste of time as I now have a good knowledge of why things work the way they do and why I am plugging which wires where.
Thanks to all that helped with this. Just got the little problem with the carbs to deal with now.
Bryanj:
Thats the thing with electrics, methodical and thought out testing and not just diving in
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