Topic: CB750 Weird Electrical Issue

[Duuuude]

Ive got a '73 750K. 30kish miles. Fairly good shape, usually doesn't give me issues.
I did my spring tune up which consisted of Quick carb check, Battery charge, Valve check, Point gap check, Cam chain adjust, New plugs, New ignition coils (I discovered I had weak spark caused by bad plug wires)

I kicked it over and it started up first kick & idled. Ran really good..until about 5 minutes later.
I went to turn my headlight on for a quick lights check and soon as I did the bike died. No sputter, No spit. Just died.

I kicked it over again, boom starts up. I go to use the horn this time it dies. At this point I try to use the electric starter to fire it up and as soon as I pressed the button I heard a little click & my electrics died.

I looked over the wiring harness up to the steering stem and cannot find any lose connectors or cuts. Not sure where to go from here...





The bike will run fine, long as I use the kick starter & do not touch any electrical switches.
I disconnected my new ignition coils & tried using a electrical component switch and am still getting the system to "trip" out.

[TwoTired]

Check battery voltage.

Cheers,

[Duuuude]

Ive got good voltage at the battery.

[rotortiller]

But is it good voltage when you press the horn button.

[rotortiller]

Good enough to support the ignition system.

[magnum56]

Good enough to support the ignition system.

"Good enough" for the ignition system alone maybe, but evidently not enough to support your lights, horn, or electric start.

 

[TwoTired]

Ive got good voltage at the battery.

What, exactly, do you consider "good"?

[Duuuude]

12.6v
^thats after spending atleast 40 minutes trying to pinpoint whats going on with the ignition key on.

[evinrude7]

12.6v
^thats after spending atleast 40 minutes trying to pinpoint whats going on with the ignition key on.

measure the voltage when you press the start button. 

[piefairy]

I'm kinda thinking its the battery as well. Have you tried raising the RPMs a bit and seeing if that allows you to use some electrics. The charging system should be able to help generate some extra amperage in the system. If that does it, then the battery just isn't putting out enough amps to run the system. Especially the started, I managed to drain my battery the other night, all the electrics worked, but when I went to hit the starter, I just got a "click" like you, but voltage was still at 12V.

[Duuuude]

Battery is fully recharged. But now I have no power when I turn the ignition on.
Checked fuses, checked connections. Tried shaking the harness. Nothing.

[BobR]

 Bad ground? I'd definitely check/clean the grounds , terminals, etc. Bob

[Spanner 1]

Corroded battery terminals, both the battery terminals and the ring terminals on the wires have to be shiny clean. Also same with your main fuse block. 'Looks clean' does not get it. Fuse clips need to be shiny brass and also grip the fuse tightly or no power. If you can pull the fuse out with your fingers = no good  The main ( 15A ) fuse filament can break under the end caps and not be visable too, good luck.