Topic: 77' 750K - Bad battery or Starter Solenoid? Electrical Help!

[SierraCB]

Howdy, looking for some insight on my on 77 750 K.

 One day after running into the store I went to hit the starter and the bike just clicked once when I hit the starter button.  After a couple mins of trying the starter and getting the same result, I decided to just kick it over to get it going and home.  Got home, checked the battery and it was at a normal 13.2 volts with the key off and dropped a volt with they key on.  So i decided to try jumping the starter solenoid with a screwdriver to make sure it was working, but no matter what I did it would spark just a little bit and not do anything.

Fast forward to today and getting some time to look at it, I installed a new solenoid to rule that out, the battery is at a full charge and checked all the fuses/connections in that area to no avail.  The lights and dash go on and off in a random way, sometimes staying on then sometimes not.  I can only get the starter relay to click if the lights do actually come on.

Any ideas around here?  Not sure where to go from here.  Could the battery still be an issue if its charged to correct voltage?

[calj737]

Loose ground wire is my bet. Especially check the RH control and around the Regulator/ Rectifier.

[newday777]

Open up the right switch assembly and inspect the starter button.  They are known to fail, burn out from too much load going through them.
Next is do you have a bunch of keys on your bike key ring? If so the ignition switch could be bad from the weight of the key ring bouncing as you hit bumps, taking out the bottom of the switch where the contacts are. 🤔

[scottly]

So i decided to try jumping the starter solenoid with a screwdriver to make sure it was working, but no matter what I did it would spark just a little bit and not do anything.

 Could the battery still be an issue if its charged to correct voltage?

Sounds like a bad battery to me. With your voltmeter connected directly to the battery terminals, check the voltage with the starter button pressed.

[HondaMan]

It could also be the fuseblock. The clips on the fuseblock are (or WERE) chromate plated in 1977, for a 10-year lifespan. Today that plating is flaking off from age, making a nice resistor that both drops the operating voltage (as measured on any BLACK wire in the harness) and heats up the fuse, often making them melt. Then they look like they "blew" for some mysterious reason.

After you check on the battery to see if it is still good, PM me if you'd like a new fuseblock with modern ATC style automotive fuses, instead.

[scottly]

No, jumping the solenoid posts bypasses the fuseblock as well as the switch, directly connecting the battery + to the starter motor. 

[RAFster122s]

Sounds like the important clue is the lights being intermittent on the warning panel...that points to bad if ignition switch in my book like Stu suggested.
Not sure why it wouldn't initiate the starter like normal when you bridge the solenoid contacts...might have 2 issues going 9n...

13.2V isn't really a full charge on a battery...so battery could be failing causing all the issues. Sounds like something to get checked out.

[newday777]

"The lights and dash go on and off in a random way, sometimes staying on then sometimes not.  I can only get the starter relay to click if the lights do actually come on.

Any ideas around here?  Not sure where to go from here.  Could the battery still be an issue if its charged to correct voltage?"

Lights going on and off randomly? Sounds like a loose connection somewhere or a random short, are you moving the harness when it happens? Have you ìnspected the harness for breaks? A bare wire or a melted connector on the harness can be problematic.
Have you load tested the battery? You said you have 13.2 volts, what are the volts when putting a load on it, headlight on and start button pushed, or using a load tester? Yes a battery can be a problem and have internal shorts when a load is put on it.

[SierraCB]

Loose ground wire is my bet. Especially check the RH control and around the Regulator/ Rectifier.

I thought it may be the main ground but there's no issue there, also checked the R/R area well and all looks good.  Nothing changes when I move things around.

Lights going on and off randomly? Sounds like a loose connection somewhere or a random short, are you moving the harness when it happens? Have you ìnspected the harness for breaks? A bare wire or a melted connector on the harness can be problematic.
Have you load tested the battery? You said you have 13.2 volts, what are the volts when putting a load on it, headlight on and start button pushed, or using a load tester? Yes a battery can be a problem and have internal shorts when a load is put on it.

Nothing changes when I move things around as if there was a random short.  The lights will be totally random without touching the bike.

Sounds like the important clue is the lights being intermittent on the warning panel...that points to bad if ignition switch in my book like Stu suggested.
Not sure why it wouldn't initiate the starter like normal when you bridge the solenoid contacts...might have 2 issues going 9n...

13.2V isn't really a full charge on a battery...so battery could be failing causing all the issues. Sounds like something to get checked out.

What am I looking for when the battery is idle/switched on/starter botton pressed?  I charged it on the tender last night and it's now reading 12.2V fully charged?  Maybe this is the issue?

Fuses all look fine to me, all be it old...
It could also be the fuseblock. The clips on the fuseblock are (or WERE) chromate plated in 1977, for a 10-year lifespan. Today that plating is flaking off from age, making a nice resistor that both drops the operating voltage (as measured on any BLACK wire in the harness) and heats up the fuse, often making them melt. Then they look like they "blew" for some mysterious reason.

After you check on the battery to see if it is still good, PM me if you'd like a new fuseblock with modern ATC style automotive fuses, instead.

[newday777]

You need to load test your battery and report your findings.

[rotortiller]

Check the battery voltage while the solenoid is engaged.

[PeWe]

Batteries can fail from one day to another.

If totally drained once due to something discharging it can be enough for a rather fresh battery to give up for good.
Can be charged but not much current for starter.

An extra battery is good to have.
I have mostly bought $50US batteries, 14Ah type.

[BenelliSEI]

Go back and read HondaMan’s advice. K7/8’s are notorious for the main fuse holder failing. Your main fuse will be loose in the clips and making little or no contact. Remove the unit and pop the back cover off. You will see the plastic is all melted and backed away from the clips, resulting in little or no clamping on the fuse ends….. Replacements are available, get a new one, or replace with a modern blade fuse unit.

[scottly]

What am I looking for when the battery is idle/switched on/starter botton pressed?  I charged it on the tender last night and it's now reading 12.2V fully charged?  Maybe this is the issue?

If the voltage, measured directly at the battery terminals, drops to lower than 10 volts when you press the starter button, without the starter turning, the battery is toast. If the voltage doesn't drop, check the battery ground connection and the positive battery connection to the solenoid.
Once again, jumping the solenoid terminals with a screwdriver bypasses the fuse block, ignition switch, and starter switch on the handle bar. The problem is either the battery or it's connections, and I'm betting on a bad battery.    

[SierraCB]

Just wanted to follow up on this, don't rule out the easiest answer and dont trust voltage alone.  Popped a new battery in and all is good to go.

Thanks everyone for your help!

[newday777]

Just wanted to follow up on this, don't rule out the easiest answer and dont trust voltage alone.  Popped a new battery in and all is good to go.

Thanks everyone for your help!

Glad you got it found out and working.

If you load test the battery it confirms of an internal short not just voltage at charge rest.