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Author Topic: 71 cb750 on off switch is working backwards  (Read 5628 times)

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Offline painters cafe

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71 cb750 on off switch is working backwards
« on: April 24, 2011, 05:20:02 PM »
theres a black wire and a black with white wire. they are pluged in but why when the red switch is off it has spark? and when it's on it dont???
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Offline Retro Rocket

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Re: 71 cb750 on off switch is working backwards
« Reply #1 on: April 24, 2011, 06:29:40 PM »
Try reversing the wires.....
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Offline painters cafe

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Re: 71 cb750 on off switch is working backwards
« Reply #2 on: April 25, 2011, 02:04:47 AM »
i did that same thing
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Offline SohRon

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Re: 71 cb750 on off switch is working backwards
« Reply #3 on: April 25, 2011, 05:50:30 AM »
If by the "red" switch you mean the kill switch, switching wires won't (or shouldn't) make a difference. The kill switch has two contacts in the center position, none on either side (this is a later switch, but the kill switches are all the same).



If you're getting power in the off position, and nothing in the center, it sounds like a rebuild is in order.
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Assembling my '74 CB550: http://forums.sohc4.net/index.php?topic=86697.0
Assembly of the Right-hand Switch (a rebuilder's guide):  http://forums.sohc4.net/index.php?topic=80532.0
Installing stock 4X4 exhaust: CB500-CB550 K: http://forums.sohc4.net/index.php?topic=82323.0
CB550 Assembly Manual: http://forums.sohc4.net/index.php/topic,151576.0.html

Offline nayto550

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Re: 71 cb750 on off switch is working backwards
« Reply #4 on: April 25, 2011, 05:50:52 AM »
This shouldn't even be possible, regardless of the wires being reversed or not.
I would suspect the switch itself first.  Grab yourself an ohmmeter and make sure the switch is closed in the "run" position and open in the "off" position.
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Offline painters cafe

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Re: 71 cb750 on off switch is working backwards
« Reply #5 on: April 25, 2011, 08:45:18 AM »
Ok ill do that. Yep it runs when it is off on kills it

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Offline Retro Rocket

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Re: 71 cb750 on off switch is working backwards
« Reply #6 on: April 25, 2011, 04:21:27 PM »
Quote from: nayto550 on April 25, 2011, 05:50:52 AM
This shouldn't even be possible, regardless of the wires being reversed or not.
I would suspect the switch itself first.  Grab yourself an ohmmeter and make sure the switch is closed in the "run" position and open in the "off" position.

Why wouldn't reversing the polarity work ?, it is only a simple switch.? I am not too sure the switch is broken if it is working exactly the opposite.....?
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Offline painters cafe

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Re: 71 cb750 on off switch is working backwards
« Reply #7 on: April 25, 2011, 04:49:08 PM »
it must be down the line black with white is at coils black is hot??? something must be cross
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Offline CBDee

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Re: 71 cb750 on off switch is working backwards
« Reply #8 on: April 25, 2011, 05:47:11 PM »
Sounds like its broken to me. Take it apart and see what gives.
« Last Edit: April 25, 2011, 05:49:58 PM by CBDee »
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Offline nayto550

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Re: 71 cb750 on off switch is working backwards
« Reply #9 on: April 25, 2011, 05:50:41 PM »
Quote from: Retro Rocket on April 25, 2011, 04:21:27 PM
Quote from: nayto550 on April 25, 2011, 05:50:52 AM
This shouldn't even be possible, regardless of the wires being reversed or not.
I would suspect the switch itself first.  Grab yourself an ohmmeter and make sure the switch is closed in the "run" position and open in the "off" position.

Why wouldn't reversing the polarity work ?, it is only a simple switch.? I am not too sure the switch is broken if it is working exactly the opposite.....?

Reversing the black/white and black wire won't work, because, as you said it is a simple switch.  Single circuit, in-line, off-on.  The only thing the switch does is cut the coils' line to power.  You can see in the wiring diagram that the switch won't care what direction it is placed in the circuit, it will still function the same.

Unless, of course, you start swapping wires with something other than the black and black/white. ;)
« Last Edit: April 25, 2011, 05:53:11 PM by nayto550 »
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Offline painters cafe

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Re: 71 cb750 on off switch is working backwards
« Reply #10 on: April 25, 2011, 06:01:02 PM »
right i'm going out and take tank off look at coil wires black and white and pull switch apart.
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Offline phil71

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Re: 71 cb750 on off switch is working backwards
« Reply #11 on: April 25, 2011, 06:07:19 PM »
take the tank off? someone must've got at that switch. Someone's got an amazing pictorial of a switch rebuild on here. From what I can see, it look like you COULD put the contacts in the wrong holes, BUT, it would be Run/off/off, or off/off/run.
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Offline hesselfuzz

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Re: 71 cb750 on off switch is working backwards
« Reply #12 on: April 25, 2011, 09:44:21 PM »
What did you do to it before this started happening?
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Offline painters cafe

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Re: 71 cb750 on off switch is working backwards
« Reply #13 on: April 26, 2011, 04:58:21 AM »
take tank off wanted to look at wires better. The controls that was on the bike had the black and b/w together switch was broke. OK this is funny I grabed one more control that i had and took light off hooked up b/w wire and black and starter y/r and tryed it SAME switch worked the same ran only when it was off turn switch to on and kills the bike. it has to be down the line somewhere dont think it's the switch??? this is a fun one
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Offline nayto550

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Re: 71 cb750 on off switch is working backwards
« Reply #14 on: April 26, 2011, 06:47:06 PM »
Bumping this thread because I'm baffled by this and am curious what others' thoughts are.
 ??? ??? ???
Has to be a short to power somewhere between the switch and the coils.  But that doesn't explain why the kill switch cuts power in the "on" position.
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Offline SohRon

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Re: 71 cb750 on off switch is working backwards
« Reply #15 on: April 26, 2011, 07:46:54 PM »
open up the headlight and by-pass the switch by disconnecting the leads running from it and jumpering the black/white main harness wire to a black lead. The bike should start and run normally. If it doesn't, you have wiring problems.

I've racked my brain and I just can't see how it could be the switch. The only electrical leads into it are the two contacts, and they're pretty well established right in the middle "run" position. I'll rerun a couple of pics to show how it goes together, but it would be real tough to get signal with the knob off the contacts.





 


Does this phenomenon occur at both "off" positions, or only one? Do all of the other electrical systems work correctly? Like the turn signals or brake lights"
« Last Edit: April 26, 2011, 08:09:44 PM by SohRon »
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Assembling my '74 CB550: http://forums.sohc4.net/index.php?topic=86697.0
Assembly of the Right-hand Switch (a rebuilder's guide):  http://forums.sohc4.net/index.php?topic=80532.0
Installing stock 4X4 exhaust: CB500-CB550 K: http://forums.sohc4.net/index.php?topic=82323.0
CB550 Assembly Manual: http://forums.sohc4.net/index.php/topic,151576.0.html

Offline painters cafe

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Re: 71 cb750 on off switch is working backwards
« Reply #16 on: April 27, 2011, 07:31:31 AM »
It work in both offs. All elec works but turns don't blink working on that one two
 
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Offline Silverback

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Re: 71 cb750 on off switch is working backwards
« Reply #17 on: April 27, 2011, 07:59:36 AM »
Quote from: rotortiller on April 27, 2011, 01:31:43 AM
Wiring issue, you are likely shorting the points out with the switch in the on position. Remember it sparks when the points open. Just a guess..........

rt

+1
Sounds like they are running a ground or something through the switch. When it's on the ground is shorting the coils/points. In the off position, the power to the coils is no longer grounded out. It seems like this configuration would blow fuses, but there are ways around that. Is this on a custom bike, or a stock bike? I have seen custom jobs with some of the craziest wiring configurations. My buddies Royal Enfield would only run if the run switch was off, turn signal switch pushed to the right and you were rubbing your belly with your left leg in the air. The PO said it was his security system.
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Offline painters cafe

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Re: 71 cb750 on off switch is working backwards
« Reply #18 on: April 27, 2011, 08:39:38 AM »
All stock 71 cb750
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