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Author Topic: 1973 CB750K3 Won't stop cranking  (Read 1682 times)

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brkbeats

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1973 CB750K3 Won't stop cranking
« on: April 14, 2009, 01:44:53 PM »
Sunday when I went to start up the bike, it would not stop cranking. I hit the kill switch, shut the power off and the bike was still trying to crank over. I had to disconnect the battery. Now if I try to hook the battery back up it starts cranking again. Does anyone have any ideas what is going on?
Thanks
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Offline 750goes

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Re: 1973 CB750K3 Won't stop cranking
« Reply #1 on: April 14, 2009, 01:53:40 PM »
Starter solenoid is stuck...
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brkbeats

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Re: 1973 CB750K3 Won't stop cranking
« Reply #2 on: April 14, 2009, 02:02:47 PM »
Is that easily fixable? I have done some work on the bike, just nothing engine related. I did get a new exhaust that I want to put on soon and by soon I mean yesterday.
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Offline 736cc

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Re: 1973 CB750K3 Won't stop cranking
« Reply #3 on: April 14, 2009, 02:41:32 PM »
ez fix is replacing solenoid from a used bike (same solenoid used on all size Hondas that period); its connected to positive battery cable. Maybe hit solenoid w/ a hammer progressively harder until something happens. Might also be stuck starter button, squirt some WD in there.
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Offline jaknight

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Re: 1973 CB750K3 Won't stop cranking
« Reply #4 on: April 14, 2009, 02:52:20 PM »
Hi brkbeats,

As 736cc says, you can get used ones (ALA Ebay or salvage yard), it is an easy replacement.

You can try taking yours apart to clean up the contact areas inside the solenoid.  Or, if you've got the money, you can get a new Honda part through sellers on the internet.  A new one from Honda is about $60.00 smackers now.

If you are going into this type of thing for the first time, the solenoid is on the left side of your bike, under the sidecover.  It should be to the right of your fuse box, just straight under the battery.  If it's a factory one, it should look very much like a flashlight "D" cell battery with 2 posts on the top of it.  One cable goes to your starter, one cable goes to Positive post of your battery.

They really are easy to work on.  I hope this helps..... ;) ;)

~ ~ ~ jaknight ~ ~ ~
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"THE PEN IS MIGHTIER THAN THE SWORD........
..........EXCEPT IN A SWORD FIGHT"
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Offline GoatBaSS

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Re: 1973 CB750K3 Won't stop cranking
« Reply #5 on: April 14, 2009, 03:54:07 PM »
smack it.
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1972 CB750K/900CC Red Headed Dunstall, 1975CB750FSS Gone BNF: 1974CB500T, 1976CB750K X 2

brkbeats

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Re: 1973 CB750K3 Won't stop cranking
« Reply #6 on: April 14, 2009, 08:42:38 PM »
Going to try the banging on it, taking it apart, and getting a spare one or two. This is getting fun to upgrade and maintain.
Thanks for the help,
Steven
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Offline HondaMan

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Re: 1973 CB750K3 Won't stop cranking
« Reply #7 on: April 14, 2009, 09:53:30 PM »
Quote from: brkbeats on April 14, 2009, 02:02:47 PM
Is that easily fixable? I have done some work on the bike, just nothing engine related. I did get a new exhaust that I want to put on soon and by soon I mean yesterday.

Yes. Search for it: I posted "how to rebuild the starter solenoid" about a year ago. Basically, remove the two screws on top of the solenoid and pull out the copper bar. Clean off the pitting, do the same to the removeable copper bolts in the cover. Clean the shaft that guides the bar up and down, oil a bit on everything, reassemble. Good for another 20 years.
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See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
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Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

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Offline Bill Vaughan

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Re: 1973 CB750K3 Won't stop cranking
« Reply #8 on: April 14, 2009, 11:09:53 PM »
As everyone has already said, it's probably the solenoid, but you might want to check the starter switch (on the handlebar control) as well.  It happened to me once due to a broken solder connection.  Easy continuity check with a meter to rule it out.
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brkbeats

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Re: 1973 CB750K3 Won't stop cranking
« Reply #9 on: April 15, 2009, 02:10:06 PM »
Fixed it. The solenoid was a bit corroded at the copper posts. Took it off cleaned it up and put it back on with out connecting terminals to copper posts. Check it by using starter button. Clicked and released. Hooked terminals up copper posts and tested again. Works great now. Gonna get a spare just in case. Thanks for the help guys.
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Offline 750goes

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Re: 1973 CB750K3 Won't stop cranking
« Reply #10 on: April 15, 2009, 02:11:18 PM »
Glad to be of assistance
 :)
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Offline jaknight

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Re: 1973 CB750K3 Won't stop cranking
« Reply #11 on: April 15, 2009, 02:43:09 PM »
Way To Go brkbeats,

Glad we could all help and happier still that you got it working.
Good job brkbeats........I'm Proud Of You! ;) ;)

~ ~ ~ jaknight ~ ~ ~
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"THE PEN IS MIGHTIER THAN THE SWORD........
..........EXCEPT IN A SWORD FIGHT"
___________________________________________
"There is nothing new under the sun.........But there are many old things we do not know"
BIBLE ---> Basic Instructions Before Leaving Earth

Offline 736cc

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Re: 1973 CB750K3 Won't stop cranking
« Reply #12 on: April 15, 2009, 03:33:05 PM »
hit it w/ a hammer anyway, show it who's the boss
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Offline Johnie

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Re: 1973 CB750K3 Won't stop cranking
« Reply #13 on: April 15, 2009, 05:42:04 PM »
Quote from: HondaMan on April 14, 2009, 09:53:30 PM
Quote from: brkbeats on April 14, 2009, 02:02:47 PM
Is that easily fixable? I have done some work on the bike, just nothing engine related. I did get a new exhaust that I want to put on soon and by soon I mean yesterday.

Yes. Search for it: I posted "how to rebuild the starter solenoid" about a year ago. Basically, remove the two screws on top of the solenoid and pull out the copper bar. Clean off the pitting, do the same to the removeable copper bolts in the cover. Clean the shaft that guides the bar up and down, oil a bit on everything, reassemble. Good for another 20 years.

Hondaman...is that post in the FAQ somewhere?
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1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

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Offline HondaMan

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Re: 1973 CB750K3 Won't stop cranking
« Reply #14 on: April 16, 2009, 07:22:09 PM »
Quote from: Johnie on April 15, 2009, 05:42:04 PM
Quote from: HondaMan on April 14, 2009, 09:53:30 PM
Quote from: brkbeats on April 14, 2009, 02:02:47 PM
Is that easily fixable? I have done some work on the bike, just nothing engine related. I did get a new exhaust that I want to put on soon and by soon I mean yesterday.

Yes. Search for it: I posted "how to rebuild the starter solenoid" about a year ago. Basically, remove the two screws on top of the solenoid and pull out the copper bar. Clean off the pitting, do the same to the removeable copper bolts in the cover. Clean the shaft that guides the bar up and down, oil a bit on everything, reassemble. Good for another 20 years.

Hondaman...is that post in the FAQ somewhere?

I don't think it got that far. Someone else had asked me how to "rebuild" one, so I made a few pix of one I'm doing for a Hondaman Special 750, and posted the instructions here. It was a year ago, I think...

I tend to call it a "starter solenoid", so maybe I'll try to search with that, in the morning (gotta go, just now, swingarms awaiting...)
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See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com

Offline Scrubs

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Re: 1973 CB750K3 Won't stop cranking
« Reply #15 on: April 16, 2009, 07:39:18 PM »
You were lucky... check what happened to me. worth bearing in mind when you shut it off
http://forums.sohc4.net/index.php?topic=37353.msg385664#msg385664


Luckily when I bought a new battery it never happened again so dident need a new solenoid after all that.
check solenoid and starter button it may be shorting.
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