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Cb750 electrical issues

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Bohater

Cb750 electrical issues

First time poster, got pretty stumped along the way of fixing my first bike, a 75 CB750K, so I thought I would tap into the wealth of knowledge that is this forum. I had just finished putting in new points (old ones were shot) and setting the static timing as well as a complete carb rebuild (PO had bigger jets and pods installed, but I put the ol' stock airbox back on). I started the bike and it ran strong, so I put it away with the ignition on accidentally. I came back and saw that the neutral light wasn't on, neither was my oil pressure idiot light (should probably fix that too). I checked the battery voltage and got a reading of 5.7 volts. Then I checked the fuses to find a 30 amp fuse in the main, and the tail light fuse blown. I did a quick check and saw one of the yellow wires from the stator was unplugged. I plugged it back in, tried a few kicks, but it wouldn't start. I check the battery again and it was now at 4.7 volts, but somehow slightly increasing. At this point, I realized that I have now idea what I am doing, and that I needed some help. Any advice or solutions will be appreciated. Thanks!

Best Regards,
Bohater

TOOLS1

Re: Cb750 electrical issues

Administrator

You need more then 4.7 volts to fire the ignition. Try charging the battery. Also check to make sure that you did not burn up one of the points sets. If one was closed while the ignition was on it could have burnt up.
TOOLS

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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
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Bohater

Re: Cb750 electrical issues

Alright I give it a go once I get home. Thanks for the advice Tools!

Bohater

Re: Cb750 electrical issues

So I charged the battery, and it'll start with the kickstart, but the starter isn't working. No noise, nothing. The horn won't work unless the bike is running, and the headlight won't turn on if it not running, and if I turn it on while it's running, the bike shuts off. So is it that my battery isn't holding enough power?

Truck

Re: Cb750 electrical issues

Sounds more like your system isn't putting out enough juice to power the bike and charge the battery.

It's only illegal if you get caught.

If at first you don't succeed, use more lighter fluid

95% of Harley Davidsons ever made are still on the road... The other 5% made it home.

New Baltimore, Va '82 CB900c, 1980 CB985F/K 'Mutt"

Re-run

Re: Cb750 electrical issues

Administrator

In reply to this post by Bohater

I would get your battery tested, for voltage and load. A fully charged batter must read 12.6 volts and hour after charging it.

Your bike, should be putting out 13.5 - 14.5 volts at about 2000 rpm. So, start the bike, and hook up a meter. Rev to 2000+ rpm and see what volts you have.

The ride IS the adventure. The destination is just to get gas!

Bohater

Re: Cb750 electrical issues

In reply to this post by Bohater

I got the battery charge and its all good. Thank you all for the advice. All I gotta do now is sync the carbs and then I can get back on the road!

Best Regards,
Bohater