Author Topic: All that work, and still I have the charging blues...  (Read 5284 times)

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Offline therager

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All that work, and still I have the charging blues...
« on: June 24, 2009, 02:53:36 PM »
Im here once more for help/inspiration on the charging system on my 78 750F.
Ive done the following to it to try to help it:

-Replaced the wiring harness. All of it, by hand, point to point, soldering any wire splices along the way.
-Removed the electrical starter, its only kick start now.
-Replaced reg/rect with a one piece/solid state item.
-Replaced the stator/field coil with one from ebay, which was from a "running bike".

Now im about to send my original stator/rotor to be rewired in Alabama.
It starts right away and will charge to 14.5v without the headlamp, but connect the headlamp and it doesnt go up past 12v.
Is there any other part I need to work on at this point or just wait for the rewired alternator to come back? What about the coils? Should I look to replace those? I know ive got after market points from the PO, could that be a culprit?
Any help is greatly appreciated.

Offline Spanner 1

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Re: All that work, and still I have the charging blues...
« Reply #1 on: June 24, 2009, 07:24:05 PM »
Well good luck with that guy in Alabama, if it's the same one I used. No communication and 6 weeks later my rotor(DOHC) came back!....however, if you still have the stator (I hope ) you can test it easily with an ohm meter. It needs to read 0.2 ohms between any of the yellow-to-yellow wires...your field coil needs to read 7.2 ohms. These readings are not good unless exactly as spec. !! Ignition points would have no effect on charging...3 ohm ignition coils will present an additional load on the system but not reduce the charge voltage to 12v...how sure are you that your battery is good ? Also, a solid state regulator may continuously vary the charge rate voltage to the battery...if the battery is full a reading of 12v might be correct ( anyone else ? ). If you leave the bike running with the h/l on does the voltage stay at 12v or drop further?
If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....

Offline Joel

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Re: All that work, and still I have the charging blues...
« Reply #2 on: June 24, 2009, 08:04:17 PM »
Im here once more for help/inspiration on the charging system on my 78 750F.
Ive done the following to it to try to help it:

-Replaced the wiring harness. All of it, by hand, point to point, soldering any wire splices along the way.
-Removed the electrical starter, its only kick start now.
-Replaced reg/rect with a one piece/solid state item.
-Replaced the stator/field coil with one from ebay, which was from a "running bike".

Now im about to send my original stator/rotor to be rewired in Alabama.
It starts right away and will charge to 14.5v without the headlamp, but connect the headlamp and it doesnt go up past 12v.
Is there any other part I need to work on at this point or just wait for the rewired alternator to come back? What about the coils? Should I look to replace those? I know ive got after market points from the PO, could that be a culprit?
Any help is greatly appreciated.


At what RPM are your voltage measurements taken?

Offline bryanj

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Re: All that work, and still I have the charging blues...
« Reply #3 on: June 24, 2009, 08:24:14 PM »
What wattage headlamp bulb
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Offline 750goes

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Re: All that work, and still I have the charging blues...
« Reply #4 on: June 24, 2009, 08:35:06 PM »
Good thought Bryan,

a bigger load from a stronger headlight will suck the life out of your charging system....

check voltage at rpms of every 1000 with light on and off (just wind the idle up as you go)..

if you have replaced all those other things - I wouldn't like a searchbeam headlight causing me any grief..

 :)

Offline therager

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Re: All that work, and still I have the charging blues...
« Reply #5 on: June 25, 2009, 06:51:59 AM »
Well I ran some measurements this morning, this is what I found:

Stator Resistance: Between any two leads would fluctuate between 0.5-0.6 Ohms, my meter is not so accurate in that range.
Field coil resistance: ~0.7ohms
Lamp: H4 12V 100/90W

Voltage at battery while running:
Light OFF:
1kRPM - 11.2V
2k - 13.4V
3k - 14.5V

ON:
1k - 11.2V
2k - 11.4V
3k - 12.1V

I didnt keep going cause if its not charging at 3k with the light on, id be dead in traffic anyway.
I did notice the battery voltage while the bike was off was 11.4V so im charging it today on the charger.
Any ideas?


Offline therager

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Re: All that work, and still I have the charging blues...
« Reply #6 on: June 25, 2009, 06:53:21 AM »
Well good luck with that guy in Alabama, if it's the same one I used. No communication and 6 weeks later my rotor(DOHC) came back!....

Did it make a difference?
Im sending the spare out to him today, talked to him on the phone, seems like a nice guy. He said he would wind it a bit hotter for me to boost the charging system...

Offline bryanj

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Re: All that work, and still I have the charging blues...
« Reply #7 on: June 25, 2009, 07:14:43 AM »
You will NEVER charge with that headlamp bulb in there as it is taking TWICE the power of the original!!!
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline HondaMan

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Re: All that work, and still I have the charging blues...
« Reply #8 on: June 25, 2009, 07:15:49 AM »
Well I ran some measurements this morning, this is what I found:


Lamp: H4 12V 100/90W



There is your problem.
Use a maximum 50/55w headlight.
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

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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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Offline therager

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Re: All that work, and still I have the charging blues...
« Reply #9 on: June 25, 2009, 07:59:24 AM »
You will NEVER charge with that headlamp bulb in there as it is taking TWICE the power of the original!!!

 :o   wow... why would the PO do that? Im off to buy a 50/55W after work, cant wait to try this! thanks again!

Offline Spanner 1

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Re: All that work, and still I have the charging blues...
« Reply #10 on: June 25, 2009, 02:24:54 PM »
That's awful you did all that work for nothing because the PO put a 100W headlight on the bike.....live and learn, I suppose.
If your sure it's a carb problem; it's ignition,
If your sure it's an ignition problem; it's carbs....

Offline therager

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Re: All that work, and still I have the charging blues...
« Reply #11 on: June 25, 2009, 02:33:50 PM »
That's awful you did all that work for nothing because the PO put a 100W headlight on the bike.....live and learn, I suppose.

Sort of. Im very excited to have a working bike (well, I still have to try replacing that bulb after work), and I have to look at the bright side... i went from knowing nada about my 750 to knowing the electrical pretty well. I can replace the alternator in ~20 minutes or so, did so this morning :)
I WOULD like to remove a glove from my hand, finger by finger, and slap the PO with it though.

ps, the $17 impact driver from my local hardare store is my new favorite tool. The $7 one from harbor freight I used before that one... my worst enemy.

Offline TwoTired

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Re: All that work, and still I have the charging blues...
« Reply #12 on: June 25, 2009, 02:47:36 PM »
Well I ran some measurements this morning, this is what I found:
Field coil resistance: ~0.7ohms
The field coil on a 750 is supposed to be 7.2 ohms.
You sure that measurement is correct?  If it is, I don't see how the alternator can be charging at all.

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Offline therager

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Re: All that work, and still I have the charging blues...
« Reply #13 on: June 25, 2009, 02:50:17 PM »
The field coil on a 750 is supposed to be 7.2 ohms.
You sure that measurement is correct?  If it is, I don't see how the alternator can be charging at all.

yer' right TT, typo there on my part, it was supposed to say ~7 ohms.

Offline HondaMan

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Re: All that work, and still I have the charging blues...
« Reply #14 on: June 26, 2009, 05:32:59 PM »
I still lust after the HID headlight that 78cb750 found: $100 German kit, beautiful stuff, lights up 2 city blocks ahead, draws 35 watts. Oh, yeah...
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

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Offline therager

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Re: All that work, and still I have the charging blues...
« Reply #15 on: June 26, 2009, 07:40:00 PM »
I still lust after the HID headlight that 78cb750 found: $100 German kit, beautiful stuff, lights up 2 city blocks ahead, draws 35 watts. Oh, yeah...

Now that sounds just about right... Is it impossible to find one anywhere?
I'd like to thank everyone again, she seems to be running perfectly now!
Here are a few shots I took on my phone as soon as she was fixed.
Im also loving the CRG lane splitters and the Rotella T oil.




Chippy569

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Re: All that work, and still I have the charging blues...
« Reply #16 on: June 26, 2009, 10:48:38 PM »
HID kits are readily available on eBay. Did you say H4 bulb? ;)
link

Offline HondaMan

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Re: All that work, and still I have the charging blues...
« Reply #17 on: June 27, 2009, 07:40:49 AM »
I would prefer the ones made in Germany: the Chinese ones have been reported here at SOHC4 to fail in short order. It sounds like the Chinese ones are, well, Chinese quality and they mechanically break.  ;)
The German ones cost about $100: I think it was 78CB750cafe that found the better ones.
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 Frankenkit

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Re: All that work, and still I have the charging blues...
« Reply #18 on: June 27, 2009, 08:54:37 AM »
Hey Hondaman, could you post a link? I think the board should know about good-quality, legal HID conversions because of the safety factor of good headlights, as well as our old charging systems.

I'd like to run one of these conversions, but only once someone else does an install write-up so I know what I'm getting into and don't have to worry about messing stuff up. :D  I've pioneered too many venues of user error. ;)

Also, FWIW, I sent my rotor/stator to Tim in Alabama, too.  They came back after a couple of weeks (I think the time est. he gave online was maybe before he got inundated by people who found out about his services)  and look beautiful.  All new harness, the orig. connectors newly welded on and sealed.  Rotor was surfaced very nicely.  My only gripes so far are that the black and white wires weren't wired 'black' or 'white' just 'yellow' so I had to guess which went to which brush, but I think that's somewhat arbitrary.  That and the new harness seems to be a slightly heavier gauge wire or something, a bit thick to wrangle through the tiny space at the bottom of the generator cover.  All that said, though, everything connected quite tightly and nicely.

I'll try and get pics of the parts.
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Offline HondaMan

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Re: All that work, and still I have the charging blues...
« Reply #19 on: June 28, 2009, 07:18:50 AM »
Hey Hondaman, could you post a link? I think the board should know about good-quality, legal HID conversions because of the safety factor of good headlights, as well as our old charging systems.

I'd like to run one of these conversions, but only once someone else does an install write-up so I know what I'm getting into and don't have to worry about messing stuff up. :D  I've pioneered too many venues of user error. ;)


Kit, here's the link: http://www.v-leds.com/Exterior-HID-FREE-SHIPPING/H4-9003-HB2/V-HID-35W-SLIM-BALLAST-p4961321.html

It wasn't 78CB750cafe, but ev0lution who found these (sorry, guys  :-[  ). They seem to be superior pieces as compared to the eBay ones from China, and I will buy one when I can scrape the $$ together. (Between jobs at the moment, oilfield bust, you know...  :-\ )
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 watson8r

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Re: All that work, and still I have the charging blues...
« Reply #20 on: March 05, 2016, 10:43:32 AM »
Hi all - I'm intrigued by the winding the stator a bit hotter comment


Well good luck with that guy in Alabama, if it's the same one I used. No communication and 6 weeks later my rotor(DOHC) came back!....

Did it make a difference?
Im sending the spare out to him today, talked to him on the phone, seems like a nice guy. He said he would wind it a bit hotter for me to boost the charging system...


has anyone had any luck getting a new stator or after market parts that put out more power?

Offline HondaMan

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Re: All that work, and still I have the charging blues...
« Reply #21 on: March 08, 2016, 11:39:04 AM »
Hi all - I'm intrigued by the winding the stator a bit hotter comment


Well good luck with that guy in Alabama, if it's the same one I used. No communication and 6 weeks later my rotor(DOHC) came back!....

Did it make a difference?
Im sending the spare out to him today, talked to him on the phone, seems like a nice guy. He said he would wind it a bit hotter for me to boost the charging system...


has anyone had any luck getting a new stator or after market parts that put out more power?

If you can find one from a CB750A bike, it drops in and makes about 40 watts more power.
« Last Edit: March 09, 2016, 04:37:57 PM by HondaMan »
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 Jerry Rxman Griffin aka MuthaF'er

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Re: All that work, and still I have the charging blues...
« Reply #22 on: March 08, 2016, 12:10:38 PM »
The 750A field coil is wound differently and might help increase the output too.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline watson8r

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Re: All that work, and still I have the charging blues...
« Reply #23 on: March 15, 2016, 12:05:14 PM »
Not sure if this was mentioned previously. I have a 400f that was crashed prior to me getting my hands on it and it had some confusing charging issues. Stator resistance and AC voltage output checked out. New Regulator and Rectifier. Checked all wiring.

In the end, the Stator coil was grounded to the frame. $65 bucks of eBay got a Stator and field coil, rotor, and Cover and the bike works like a charm.

Big shout out to Oregon Motorcycles for thinking of the stator being grounded to the frame.