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Author Topic: 76 CB750F Electrical  (Read 1160 times)

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Offline J.earhart

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76 CB750F Electrical
« on: August 28, 2018, 11:29:33 AM »
Hello everyone, I thought I would get a straight answer before I start tearing into things. Location of the charging components in my SOHC? A shop told me it's in the front right of my engine but, my electronic ignition wiring goes in there. I thought it was in the front left of the engine. Also, I could use some wiring help. In my amazing wisdom due to not labeling (mixed with confusing wiring from a previous owner) I am not sure what wiring is suppose to go in the little honda box and where it mounts onto the bike. I bought a brand new wiring harness and I am just replacing it. On that note, my harness came with a tiny brown with a blue stripe wire....any ideas where that one is suppose to go?
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Offline Bankerdanny

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Re: 76 CB750F Electrical
« Reply #1 on: August 28, 2018, 12:06:58 PM »
Left front is where the alternator is, then wires run under the left side engine covers to behind the left sidecover where the electrical panel and fuses are. These bikes use a 2 piece rectifier and regulator are part of the panel there.
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"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline Bankerdanny

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Re: 76 CB750F Electrical
« Reply #2 on: August 28, 2018, 12:14:04 PM »
This is under the left sidecover of my '76 750F with the fuse block removed. The circle is (I believe) the rectifier and the voltage regulator is behind that.
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"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline DHuffman

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Re: 76 CB750F Electrical
« Reply #3 on: August 28, 2018, 03:18:34 PM »
Quote from: Bankerdanny on August 28, 2018, 12:14:04 PM
This is under the left sidecover of my '76 750F with the fuse block removed. The circle is (I believe) the rectifier and the voltage regulator is behind that.

I believe the circled portion is the regulator, and that the rectifier is the small rectangular  piece down to the left of it.
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Offline DHuffman

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Re: 76 CB750F Electrical
« Reply #4 on: August 28, 2018, 03:21:12 PM »
Quote from: J.earhart on August 28, 2018, 11:29:33 AM
Hello everyone, I thought I would get a straight answer before I start tearing into things. Location of the charging components in my SOHC? A shop told me it's in the front right of my engine but, my electronic ignition wiring goes in there. I thought it was in the front left of the engine. Also, I could use some wiring help. In my amazing wisdom due to not labeling (mixed with confusing wiring from a previous owner) I am not sure what wiring is suppose to go in the little honda box and where it mounts onto the bike. I bought a brand new wiring harness and I am just replacing it. On that note, my harness came with a tiny brown with a blue stripe wire....any ideas where that one is suppose to go?

Here is the wiring diagram for your '76 CB750F.

http://manuals.sohc4.net/cb750f/technical_reference/WD750F_75_76.pdf
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Offline J.earhart

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Re: 76 CB750F Electrical
« Reply #5 on: August 28, 2018, 04:50:36 PM »
hey everyone, thanks for your replies!

this is the box i speak of:

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Offline Bankerdanny

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Re: 76 CB750F Electrical
« Reply #6 on: August 28, 2018, 04:54:56 PM »
That is where the main harness connector and the connectors for turn signals, gauge lights  and warning lights go
« Last Edit: August 29, 2018, 10:50:29 AM by Bankerdanny »
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"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline J.earhart

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Re: 76 CB750F Electrical
« Reply #7 on: August 28, 2018, 05:31:29 PM »
do they also go through the headlight housing?
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Offline Bankerdanny

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Re: 76 CB750F Electrical
« Reply #8 on: August 29, 2018, 06:39:01 AM »
Quote from: J.earhart on August 28, 2018, 05:31:29 PM
do they also go through the headlight housing?

Mostly no.
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"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline TwoTired

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Re: 76 CB750F Electrical
« Reply #9 on: August 29, 2018, 09:33:20 AM »
There are a lot of Honda wire color code function descriptions in the FAQ.

Why don't you have a shop manual for the bike you are working on?

Cheers,
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Bankerdanny

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Re: 76 CB750F Electrical
« Reply #10 on: August 29, 2018, 11:10:44 AM »
The brown wire with the blue stripe goes to the turn signal buzzer.

If you PM me an e-mail address I can send you a very nice color wiring chart. It's for the 77-78 F models, but works fine on the '76. I used it to reconnect all my wiring. If you have access to a color copier it also prints up nicely on 11x17 paper for a big easy to read diagram.

Here's some useful pictures and diagrams for how to route things.

The last 2 pictures are from the 750F supplement to the repair manual that you will find in the manuals section of the forum.
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"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline DHuffman

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Re: 76 CB750F Electrical
« Reply #11 on: August 29, 2018, 04:36:05 PM »
Also, if you want to replace those old regulator and retifiers, I have a new Rick's Regulator/Rectifier combo that I'll sell you.
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Offline J.earhart

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Re: 76 CB750F Electrical
« Reply #12 on: August 29, 2018, 05:52:21 PM »
Quote from: DHuffman on August 29, 2018, 04:36:05 PM
Also, if you want to replace those old regulator and retifiers, I have a new Rick's Regulator/Rectifier combo that I'll sell you.

Thank you for the offer!! I already bought one and have it installed though!

Thank you all for the advice and help so far! This is the most helpful forum I have ever been on. Anything to watch out for when it comes to changing my alternator? Never done one on a bike! I would also like to change the harness if it is easily done as I have a new one.
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Offline Bankerdanny

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Re: 76 CB750F Electrical
« Reply #13 on: August 29, 2018, 06:58:48 PM »
Quote from: J.earhart on August 29, 2018, 05:52:21 PM
Quote from: DHuffman on August 29, 2018, 04:36:05 PM
Also, if you want to replace those old regulator and retifiers, I have a new Rick's Regulator/Rectifier combo that I'll sell you.

Thank you for the offer!! I already bought one and have it installed though!

Thank you all for the advice and help so far! This is the most helpful forum I have ever been on. Anything to watch out for when it comes to changing my alternator? Never done one on a bike! I would also like to change the harness if it is easily done as I have a new one.

Why do you think that you need to replace the alternator? They almost never fail. Don't be making extra work and expense for yourself needlessly.
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"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline J.earhart

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Re: 76 CB750F Electrical
« Reply #14 on: August 29, 2018, 08:18:09 PM »

[/quote]

Why do you think that you need to replace the alternator? They almost never fail. Don't be making extra work and expense for yourself needlessly.
[/quote]

When I put a volt meter to the bike and reved the bike over 2k and held it steady, it never rose in V. I always thought that a bad regulator and rectifier would show an “overcharge.”
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Offline Bankerdanny

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Re: 76 CB750F Electrical
« Reply #15 on: August 29, 2018, 08:26:18 PM »
A bed regulator can go either way. My 550 wasn't charging and installing the Rick's unit fixed that. Install the unit and make sure all connections are clean and then test.
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"The problem with quotes on the Internet is that you never know if they're true" - Abraham Lincoln

Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline J.earhart

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Re: 76 CB750F Electrical
« Reply #16 on: August 30, 2018, 07:55:34 AM »
I was able to get it running (runs like crap) but, it showed that over 2k rpm it was just over 13v so it is charging! The next issue to solve is why it is running so poorly. My thought would be the wiring since the coils get warm. I have looked over the wiring diagram and I think my coils may be on the wrong side? Everything seems to be hooked up properly.
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Offline J.earhart

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Re: 76 CB750F Electrical
« Reply #17 on: August 30, 2018, 07:59:54 AM »
MORE PICTURES.
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Offline J.earhart

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Re: 76 CB750F Electrical
« Reply #18 on: August 30, 2018, 08:16:47 AM »
Just as an fyi for everyone, I only have the ignition system and charging system hooked up so I can turn the key and start to test the charging etc.
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