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Author Topic: 1978 CB 750f Fires but only a few times then quits  (Read 7846 times)

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Offline apetersonboy

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1978 CB 750f Fires but only a few times then quits
« on: February 12, 2014, 03:51:22 PM »
My 1978 CB 750f solenoid clicks once when I press the start switch, but engine won't turn over.

My bike is in neutral, and I have the clutch lever pulled in all the way.
I don't think it is the battery: I have it hooked up to a car battery that's fully charged.
Any ideas?
« Last Edit: February 16, 2014, 05:48:26 PM by apetersonboy »
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Offline Stev-o

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #1 on: February 12, 2014, 05:32:45 PM »
Sounds like a dead battery. Try jumping the solenoid....
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Offline krusty

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #2 on: February 12, 2014, 05:36:37 PM »
I had the same problem with my F2 when I tried to jump it from a car battery after it had been sitting 15 years or so. Turned out the jumper leads had frayed where they clamp to the clips. Refreshed all the end connections and all was good again.
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Offline Medyo Bastos

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #3 on: February 12, 2014, 05:50:21 PM »
short across the solenoid posts with a screwdriver and see if it will start...
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Offline apetersonboy

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #4 on: February 12, 2014, 07:01:38 PM »
I tried jumping across the terminals on the solenoid. No luck.

But when I put the positive terminal on a bolt that goes into the frame while the negative cable is still hooked up to the ground wire, the bike turned over and lit up and everything. What does this mean?
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Offline Stev-o

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #5 on: February 13, 2014, 07:11:03 AM »
Quote from: apetersonboy on February 12, 2014, 07:01:38 PM


But when I put the positive terminal on a bolt that goes into the frame...

You hooked up the positive to ground??
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Offline MoMo

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #6 on: February 13, 2014, 07:24:57 AM »
Quote from: Stev-o on February 13, 2014, 07:11:03 AM
Quote from: apetersonboy on February 12, 2014, 07:01:38 PM


But when I put the positive terminal on a bolt that goes into the frame...

You hooked up the positive to ground??




I read it that way too Stev-O...Larry
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Offline apetersonboy

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #7 on: February 13, 2014, 08:34:22 AM »

Quote from: Stev-o on February 13, 2014, 07:11:03 AM
Quote from: apetersonboy on February 12, 2014, 07:01:38 PM


But when I put the positive terminal on a bolt that goes into the frame...

You hooked up the positive to ground??

It happened on accident at first. I was messing with the air box and the positive lead got pushed on a battery box bolt and to my surprise the bike turned over.


Sent from my iPod touch using Tapatalk
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Offline MoMo

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #8 on: February 13, 2014, 11:15:19 AM »
check all your grounds, especially the negative battery cable.  Lucky you didn't fry parts of the harness...Larry+
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Offline apetersonboy

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #9 on: February 13, 2014, 12:47:35 PM »
Quote from: MoMo on February 13, 2014, 11:15:19 AM
check all your grounds, especially the negative battery cable.  Lucky you didn't fry parts of the harness...Larry+

The negative cable for the battery is supposed to be connect to the one coming out of the engine on the right side by the sprocket, correct? Just making sure I'm even using the correct cable to ground it.
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #10 on: February 13, 2014, 01:41:45 PM »
Wait a minute, the negative battery terminal cable connects to the top rear engine hanger bolt on the right side. Make sure you clean paint and rust off as well as clean the eye on the end of the cable too. The other cable coming from the LEFT side by the sprocket goes to your solenoid opposite the positive battery cable. Sit on your bike and left leg is on left side.
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Offline cheftuskey121

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #11 on: February 13, 2014, 01:42:55 PM »
no sir! that is the positve from the starter! that needs to be connected to one of the solenoid contacts. the other solenoid contact goes to battery positive.

the negative battery terminal goes to frame ground behind the engine on the frame. use the engine mounting bolt. 

Jerry beat me to it!
haha
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Offline apetersonboy

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #12 on: February 13, 2014, 02:45:46 PM »
Oh my. Thank you guys a lot!!!  ::) :)
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Offline apetersonboy

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Re: 1978 CB 750f Fried Speedometer
« Reply #13 on: February 14, 2014, 10:09:29 AM »
Quote from: MoMo on February 13, 2014, 11:15:19 AM
Lucky you didn't fry parts of the harness...Larry+


Pretty sure I fried my speedometer. All the wires are receiving power from the harness, I checked. But, none of the idiot lights light up now. The illumination light on flickers on for a split second as the key is in between the on and off position while in the act of being towards to off. I tried to take the speedo apart to check it out, but it wouldn't come apart. Any suggestions? I think I will email DCC as that's where I got it from.
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Offline iron_worker

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #14 on: February 14, 2014, 11:01:31 AM »
Hooking up the battery in reverse will do that ...  :o

IW
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Offline apetersonboy

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #15 on: February 14, 2014, 12:03:22 PM »
Quote from: iron_worker on February 14, 2014, 11:01:31 AM
Hooking up the battery in reverse will do that ...  :o

IW

Learned my lesson I guess :P Do you think it's something that could be repaired?
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Offline iron_worker

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #16 on: February 14, 2014, 12:23:20 PM »
I'm guessing it's some sort of aftermarket all in one unit?

IW
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Offline apetersonboy

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #17 on: February 14, 2014, 12:24:51 PM »
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Offline LesterPiglet

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #18 on: February 14, 2014, 12:36:42 PM »
You've nothing to lose trying to fix the lights yourself then. I see some sort of bung where the wires enter. I'd try and get it out.
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Offline Medyo Bastos

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #19 on: February 14, 2014, 12:51:23 PM »
dont beat yourself up too bad.  that is an honest mistake.  now you know better  ;D
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Offline Stev-o

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #20 on: February 14, 2014, 03:05:12 PM »
Dont need no stinkin speedo. Is the bike running now??
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Offline LesterPiglet

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #21 on: February 14, 2014, 03:08:32 PM »
Quote from: Stev-o on February 14, 2014, 03:05:12 PM
Dont need no stinkin speedo. Is the bike running now??
Can you ride legally without a speedo?
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'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


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Offline Stev-o

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #22 on: February 14, 2014, 03:10:08 PM »
Quote from: LesterPiglet on February 14, 2014, 03:08:32 PM
Quote from: Stev-o on February 14, 2014, 03:05:12 PM
Dont need no stinkin speedo. Is the bike running now??
Can you ride legally without a speedo?

It's only illegal if ya get caught!  Are your coppers that strict, Les?
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Offline SOHC4 Cafe Racer Fan

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #23 on: February 14, 2014, 03:15:35 PM »
Grounds for impounding in CA. :(
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Offline LesterPiglet

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Re: 1978 CB 750f Solenoid click but engine won't turn over.
« Reply #24 on: February 14, 2014, 03:19:58 PM »
Quote from: Stev-o on February 14, 2014, 03:10:08 PM
Quote from: LesterPiglet on February 14, 2014, 03:08:32 PM
Quote from: Stev-o on February 14, 2014, 03:05:12 PM
Dont need no stinkin speedo. Is the bike running now??
Can you ride legally without a speedo?

It's only illegal if ya get caught!  Are your coppers that strict, Les?
Oh yes. It's part of our annual MOT. Though they can't tell if it works unless they ride it.   ;D
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'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


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