Charging

Gacataki

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Morning All, and Happy New Year.

Please could I get help with worst possible problem (for me anyhow).

I can ride my 1980 750 Custom sometimes, and everything is good. Battery spins the starter like crazy, and bike starts. Other times the battery is basically completely dead, and I have to push start. The bike starts immediately. I'm not sure if it is just not charging sometimes, or if the battery is being drained by something. When it does this, the battery goes flat very quickly - even after a 3minute ride. Please help.
 

jpdevol

CB750 Enthusiast
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Good Morning.

The intermittent nature of your issue might be a number of things, but the fact that it primarily affects starter, I'd check that circuit first. If the bike starts by pushing, there must be some battery voltage or the ignition would not fire, so my first suspicion is a bad connection on the starter circuit: battery positive to solenoid, solenoid to starter motor or a bad ground connection from battery negative to frame, frame to engine (starter motor is grounded via engine). I would check, clean and tighten all those connection points.

Once running, check charging voltage across battery terminals and see if it is 14.5VDC @ ~2500rpm.

To check for an electrical drain while shut-off, you need to connect an ammeter (set to milliamps) in series between battery (-) and its ground cable (disconnected).
 

manya2

CB750 Member
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Thanks. Where would I find the safety switch?
It's on the wire harness and it's red next to the battery . Try to jump the starter solenoid on top w/ screw driver to see if starts. The safety unit some times goes bad and you can't start the bike. Does not let you started if is in gear or running. may not be your problem , it would be your last chance. Good luck !
 
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