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will not keep the battery charged

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houston.hey

Re: will not keep the battery charged

I have the same bike - 78 cb750K, and having the same problem. Bought a multimeter today to try and diagnose. Hoping the problem isn't the stator, as it looks like the pre-79 stators are no longer made, and hard to find. 2 questions:

1. where can I find a 78 cb750K stator?
2. Is the alternator on a 78 a permanent magnet setup?

Looks like we're in this together, any help is appreciated!

dana5169

Re: will not keep the battery charged

anyone still reading this thread. I have this same issue. I have a '78 CB750K. Mine is only putting out about 9 volts at idle. It goes up close to 12 somewhere around 3k. My regulator was putting out around 10.3 volts at idle. I jumped that wire to 12 volts and the voltage at the battery only went up to 11. To me, that tells me that either the stator or rotor is bad, but I could be wrong. Hey, it happened once. :)
Any other ideas?

TOOLS1

Re: will not keep the battery charged

Administrator

Sounds like the regulator is not working. It might just need adjusted. Shiny did a writeup on adjusting them awhile back. I am sure if you do a search, you will find it.
TOOLS

Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."

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
South of Eden (Kansas City MO)

houston.hey

Re: will not keep the battery charged

In reply to this post by dana5169

Start with the battery. How new is it? is it fully charged? Do you know for sure that it is holding a full charge?

On Jun 8, 2015, at 6:09 PM, dana5169 [via Honda CB750'S] <[hidden email]> wrote:

anyone still reading this thread. I have this same issue. I have a '78 CB750K. Mine is only putting out about 9 volts at idle. It goes up close to 12 somewhere around 3k. My regulator was putting out around 10.3 volts at idle. I jumped that wire to 12 volts and the voltage at the battery only went up to 11. To me, that tells me that either the stator or rotor is bad, but I could be wrong. Hey, it happened once. :)
Any other ideas?

If you reply to this email, your message will be added to the discussion below:
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NAML

houston.hey

Re: will not keep the battery charged

In reply to this post by TOOLS1

"Sounds like" will get you in trouble with electrical. Be SURE, before repair parts..

On Jun 8, 2015, at 7:28 PM, TOOLS1 [via Honda CB750'S] <[hidden email]> wrote:

Sounds like the regulator is not working. It might just need adjusted. Shiny did a writeup on adjusting them awhile back. I am sure if you do a search, you will find it.
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run

1976 CB 750-A X 2
1977 CB 750-A X 2
1977 CB 750-K X 2
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
South of Eden (Kansas City MO)

If you reply to this email, your message will be added to the discussion below:
http://honda-cb750-s.456789.n3.nabble.com/will-not-keep-the-battery-charged-tp461428p4056932.html

To unsubscribe from will not keep the battery charged, click here.
NAML

shinyribs

Re: will not keep the battery charged

Administrator

In reply to this post by dana5169

Seriously doubt your rotor is bad. Sohc rotors are literally just a huge lump of steel.

You're getting voltage rise when revved, which points to an operating stator.

You're getting DC voltage, so your rectifier is fine.

Low voltage is an indicator of a "weak" regulator. Like Tools said, it probably just needs adjusting, which is very easy. If you can't find the info you need on here by searching either look out up in the FSM or shout and I'll see if I can look you to it.

Search " adjusting your charging system " ??? Really can't remember.