Author Topic: '77 CB750A electrical (need pic help) Pics are posted on facebook...  (Read 3863 times)

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Offline stresssolutions

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Thanks for reading.  my first attempt to post pics in a thread, hope it works.  In the event it does not work, can you post a pic of diodes and rectifiers so I can be sure I know what they are?  thanks.

I've got a honda service manual and a Clymers, but I'm still having some trouble identifying some items.  Got a question or 2 about some things too.

I removed a couple of those wire taps, where the insulation is pierced.  Would you chop the wire and splice it, or just insulate that spot somehow, and how would you do it?

In the headlight wiring, the white wire looks like it was smashed, should I cut that part out/splice it just in case?  no pic yet.

There is a pic that shows some cut wires, anyone know where they were going/coming from?  There is an item above the carbs with 2 wires, what is it?  Which is the rectifier?  Diodes?  Should I replace the battery cable or just clean it up?  thanks
« Last Edit: February 01, 2009, 07:27:29 PM by stresssolutions »
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Offline stresssolutions

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Offline Spanner 1

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Re: '77 CB750A electrical (need pic help) Pics are posted on facebook...
« Reply #2 on: February 01, 2009, 08:10:21 PM »
O.K....pic.57= turnsignal flasher unit
pic.58= you can insulate with good quality electrical tape if the copper is not 'nicked'
pic.59= throttle cable ?
pic.60/61= choke cable....I'm not sure what your Q's are about these items.
If your sure it's a carb problem; it's ignition,
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Offline TwoTired

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Re: '77 CB750A electrical (need pic help) Pics are posted on facebook...
« Reply #3 on: February 01, 2009, 10:15:18 PM »
I removed a couple of those wire taps, where the insulation is pierced.  Would you chop the wire and splice it, or just insulate that spot somehow, and how would you do it?
The wire taps (I hate those things) chew off insulation.    You kind of have to look into the insulation damage and see if the wires inside are still undamaged, un-corroded.  If not, then you get some liquid vinyl or liquid tape to seal it back up for a long lasting repair.  I think this is better, neater, and more stable in weather environments than ordinary electrical tape.  The tape adhesives don't seem to fare as well, long term, as the liquid tape.

http://www.caswellplating.com/aids/plastidip.html

I cannot see pics in facebook, (requires login).

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Offline stresssolutions

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Re: '77 CB750A electrical (need pic help) Pics are posted on facebook...
« Reply #4 on: February 02, 2009, 03:58:39 AM »
I'll keep trying to post the pics here, as well. 

I was thinking the liquid tape for those tailight wires...I just recently took those taps off.  One wire ran to the front of the bike and was spliced 9 times.
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Offline fishhead

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Re: '77 CB750A electrical (need pic help) Pics are posted on facebook...
« Reply #5 on: February 02, 2009, 04:41:46 AM »
The second picture is the 7 Volt regulator. It turns the solenoid on and off that is between 1 & 2 carbs. That electrical solenoid controls the vaccum that is applied to the vaccum pull off (soleniod) that is between 3 & 4 carbs. The vaccum solenoid controls the idle speed when the bike is put in gear and keeps the bike from stalling at idle and in gear.
 Your carbs (CB750A) should look like this with the electrical solenoid between 1 and 2 and the vaccum solenoid between 3 and 4. The picture sucks though.
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Offline TwoTired

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Re: '77 CB750A electrical (need pic help) Pics are posted on facebook...
« Reply #6 on: February 02, 2009, 11:39:02 AM »
About those cut wires...
Skin back the outer insulation so you can identify the color code of the wires.

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Lloyd... (SOHC4 #11 Original Mail List)
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Offline Spanner 1

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Re: '77 CB750A electrical (need pic help) Pics are posted on facebook...
« Reply #7 on: February 02, 2009, 02:34:23 PM »
Some more on your pics.
Pic. 50 is the 'speed warning unit ', pic.54 is the regulator, pic.55 is the rectifier.
B.T.W., the 7 volt regulator is on the left side and it feeds the 7v to the gas gauge and its sender ( in the tank), only. Fishead is right about the solenoid for the  Neutral idle/ drive idle but it gets a signal when you click into L or D...the load of the transmission trying to creep the bike forward when engaged is enough to lower the idle-speed to where it will stall-out, hence the need to increase idle when 'in gear' ! When the solenoid opens it allows vacuum to the diaphragm ( as described by Fishead ) which lifts the throttle slightly and has its own adjustment set-screw , its covered with a soft plastic, remove to adjust. you can see it between carb. 3 and 4. Its loads of fun with a 750A !
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Offline stresssolutions

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Re: '77 CB750A electrical (need pic help) Pics are posted on facebook...
« Reply #8 on: February 10, 2009, 04:09:41 AM »
In the process of finding and correcting different things.  Things like green on the red wires going into the fuse block plug.  Burnt connectors on the ignigion switch.  Fun little stuff.

Horn has always been puny at best, sick at times, usually can fart louder than the horn.  Does the copper on the button wear away to the point that it doesn't make contact?  And if so, do you just put a spot of solder on there to build it up?  Or buy a new one somewhere?  I suppose I could snag one at the salvage yard. 

What is the electrical device above and behind the fuse block?  thanks.
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Offline stresssolutions

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Re: '77 CB750A electrical (need pic help) Pics are posted on facebook...
« Reply #9 on: February 10, 2009, 08:53:35 AM »
Another dumb question.  How do you test a horn?  pos and neg across the terminals cause a tiny blip, nothing else I can think of causes any reaction. thanks
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Offline Spanner 1

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Re: '77 CB750A electrical (need pic help) Pics are posted on facebook...
« Reply #10 on: February 10, 2009, 03:06:52 PM »
The device above the fuse-block is the 7v reg....see my previous post..
Your horn is just 'stuck'... press the center ( front ) with your thumb, see if it will move slightly, also tap the back with a  screwdriver handle connect it up and try again. Repeat until loud ! I'm sure your button is fine.
If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....