1981 cb 750k starter help

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1981 cb 750k starter help

Ecwil
I just got an old one that has not started in a while. Want to check compression before I put to much money into her.  Have a battery charger that is reading 13v hocked to the battery. All lights are on and I hit the starter button. I hear a click in the starter solenoid and lights dim.  With volt meter on the starter side of the solenoid I find out I am only getting 5v so I have a bad solenoid. I then try to by by-past the solenoid and I still get nothing out of the starter. The starter is good I took it out and checked it.  I am at a loss. How do you check a starter ground? What else should I do?  This is my first post and I am glade to find this forum. Thanks for the help.
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Re: 1981 cb 750k starter help

TOOLS1
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It really sounds like the starter is bad to me because it should have worked when you by-passed the solenoid. There are two other things that might cause this. One is the battery cable being corroded inside the insulation, and secondly the engine is locked up. Have you tried cranking the engine over with a wrench on the end of the crank?
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)
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Re: 1981 cb 750k starter help

Ecwil
In reply to this post by Ecwil
I have pushed it when it is in gear and it will turn and acts like it should.    
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Re: 1981 cb 750k starter help

Ecwil
In reply to this post by Ecwil
When i took the starter out i brought it down to advance auto and it worked when they put power to it.
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Re: 1981 cb 750k starter help

Ecwil
In reply to this post by TOOLS1
Part two.  I put another battery on it and I got a little noise out of the starter.  I must not have been getting enough amps with the set up I was using.  The starter did turn but it sounded slow.  I took the plugs out and the starter turns the bike like I imagine it should.  When the plugs are in it it is slow to turn it over. does this mean i have a bad valve that is creating to much  compression?  Or can a starter spin ok when it is has no load and then slow when it does?  When I brought it to advance auto to test the starter he said it sparked and that means it draws a lot of power.  I would prefer a bag starter to a top end.
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Re: 1981 cb 750k starter help

TOOLS1
Administrator
Sounds like you need a new battery.
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)
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Re: 1981 cb 750k starter help

motogrady
Administrator

maybe take a jumper cable, or a wire about the same as is on the bike,
with everything installed, and jump right from pos on the battery,
to the lug on the starter.  bypass all the existing/old wire and connections,
if it works like that, bad something between starter and switch.

The ground, if theres no paint or crud between starter and frame,
and the jumper thing doesn't work I'd agree with Tools, battery.
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Re: 1981 cb 750k starter help

Ecwil
 Thanks for all of your suggestions.   I have put a new battery into the bike.  Things got a little better.  Now I hit the starter button and I get a little movement from the starter. It sounds like it is tired or not enough push from the battery still.  I have taken the starter out and I will try to get it tested again this time under a load.  Can a starter be bad under load and still spin good with power to it? The place I have had test the starter is a car parts store and I do not know if there is a difference in testing a car starter at 12 volts and a bike starter at 12 volts.
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Re: 1981 cb 750k starter help

LukeM
Administrator
For troubleshooting purposes, you can use a car battery in parallel with your MC battery.  DO NOT HAVE THE ENGINE RUNNING IN YOUR CAR WHILE DOING THIS. The car alternator typically puts out way more amps than the bike can handle. I agree with pulling the starter, and putting cables on the starter + post and case.  It should spin freely. You may have bad brushes or a bad bearing if it only spins slowly.  Also, check the gear chain inside the side cover.  There is an over-running clutch inside, and sometimes the bolts for the clutch come loose from the side of the crankshaft. You will get some oil leakage while doing this last step.

Hope this helps.
Luke M

Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.
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Re: 1981 cb 750k starter help

Ecwil
Thanks for your help.  The gear chain you wrote about. Where is it. I have an 81 with dohc. I can turn the back wheel when it is in 5th gear.(easer to do with plugs out). I ask because last time I took the left Sid cover off I do no remember a chain. The mind is the first to go.  Thanks again
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Re: 1981 cb 750k starter help

TOOLS1
Administrator
The DOHC does not have a chain for the starter. It is gear driven.
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)
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Re: 1981 cb 750k starter help

LukeM
Administrator
In reply to this post by Ecwil
No chain per se: the gears are inside the left side cover at the bottom of the engine. You should see if pretty plainly in the FSM (which I assume you've already downloaded). While you're at it, you could test the starter in the chassis by removing the middle gear, and cranking the engine.  A good chassis ground is essential for the starter to spin up to full power.

Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.
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Re: 1981 cb 750k starter help

Johnnylevi
In reply to this post by Ecwil
http://www.youtube.com/watch?v=bw0CSzMNSXk You may not need to rebuild it. Just tighten those 3 bolts and use some red loctite on it. Hope this helps
1981 SS with Kerker 4-1 exhaust and extremely attractive rider.
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Re: 1981 cb 750k starter help

Ecwil
Thanks for all the help. I tightens everything up inside and it works great. The brushes needed to be tightened. You could tell that it had been drawing a lot of juice because it looked like things got hot in there.  Now it is on to the fuel problem. Thanks again for the help. I will probably have another post in a couple of days about  cr carb options.  
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Re: 1981 cb 750k starter help

LukeM
Administrator
Glad to hear it.  There are rebuild kits out there for Honda starters, and they're not hard to install, or very expensive.  I need to rebuild the old one from my Shadow: just don't have the time.

As for the carb issues, if you can, get it as close to stock as you can: factory airbox, filter, base settings for mixture and so forth.  The process as detailed in the FSM should work for you.

Good luck, and keep us in the loop.  You're doing good...just a few more things to touch, and soon, you'll be riding!

Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.