Hey guys, i am new to this forum and hoping to gain some knowledge on my bike that i am having trouble with. I have a 81’ honda cb750k and it runs beautifully but am having issues battery wise i bought a new battery for the bike as the one it had before was dead and with the new battery the bike cranked over nicely and rode great for a while but a day or two later after a good ride i parked the bike to get some lunch and when i came back the battery was dead. I left nothing on so i was a bit confused i got the battery recharged and everything seemed great battery held charge but when i put it on the bike and had a good ride and parked it the bike died on me again. Im not sure where to start my bike has this weird 2 kill switch side thing so i am not sure if there would be an issue there i hope someone could enlighten me
Welcome. The DOHC bikes are known for having bad charging systems, so that is the place to start. You can test it with a cheap Ohm meter, With the bike running attach the leads to the battery terminals and rev the engine to 3000 RPM. The meter should show 13.4 volts. If it is less you probably have a bad rotor or stator. Both can also be tested with the Ohm meter.
I would recommend that you download the Honda factory service manual from the manuals page. It has detailed instructions on testing the charging system components.
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1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
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1973 CB 350
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As Tools said, it is a weak point on these bikes. The service manual will show you how to test both. One thing I would do, is to go through all the connectors and clean them up, make sure they make a solid connection. It is possible that a connection is bad, not likely, but possible. Still, clean/tight connections will help prevent future issues. Also, test the regulator/rectifier. Occasionally, those can have troubles.
The ride IS the adventure. The destination is just to get gas!
The "weird" run/stop switch is standard for this period Hondas, and only interupts the ignition. As they said, check all connections. While doing so, also inspect the wire/connector interface for signs of corrosion or heating.