Re: Electric starting problems - 82 cb750

Posted by sgtslag on Jun 30, 2012; 7:22pm
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/Electric-starting-problems-82-cb750-tp4023957p4023969.html

Actually, it sounds like your charging system is not working, so your bike was running off of the battery's current, only.  In other words, check the battery's voltage (as stated already, it should be 12.6 Volts, but I guarantee it isn't anymore); charge the battery to full, then try turning it over.  With a fully charged battery, it will very likely start, as normal.

Once it is running, put a voltmeter across the battery terminals, and open the throttle to run the engine up to 3,000 RPM.  At 3,000 RPM, the charging system should be pumping around 13.5 to 14+ volts into the battery...

If you get less than 13.5 to 14+ volts, with the engine idling at 3k RPM, then it is your charging system which is failing.  There are several possibilities here:  the Rectifier/Regulator may be blown, or the alternator is bad, or there is a wiring problem.  To properly troubleshoot it, I would recommend following the guidelines within the FSM (Factory Service Manual), found on the Home Page of this site, as a free download.

Take some time to read up on the troubleshooting process, then give it a whirl.  Get back to us with what you find, and if you have questions, we would be happy to help out.  Cheers!