Topic: first ride: 1976 CB750F. now tuning / charging issues

[riffman12]

I can not tell from the picture clearly, but a Yellow wire on your rectifier (the picture I copied above) looks to have some shielding knocked off? That needs to be repaired if so.

The male spades on your Regulator need to be shiny and bright, as do the corresponding females.

You can order (www.vintageconnections.com) a kit of plastic connectors and spades/bullets that are stock replacements. Do that and replace/repair any brittle or burnt connections, put shielding on where missing, and clean the connections well before you buy a harness.

Some wrist grease (its not as tough as elbow) and a multimeter, and a few hours, and you might just find your bike works a treat-

Hm I'll have to check in person on that shielding when I get home tonight. I'm thinking of getting a regulator/rectifier combo to knock out some of the dirty pieces here. That should also replace some of my connections.

Yeah Riff, you got some cleanin' to do. 

How does your fuse holder look...front and back.

Haha yeeeeah it's pretty gross.

I bought a brand new fuse holder from HondaMan to get blades, so that's the one clean part.

Think it's salvagable?

[flybox1]

I can not tell from the picture clearly, but a Yellow wire on your rectifier (the picture I copied above) looks to have some shielding knocked off? That needs to be repaired if so.

The male spades on your Regulator need to be shiny and bright, as do the corresponding females.

You can order (www.vintageconnections.com) a kit of plastic connectors and spades/bullets that are stock replacements. Do that and replace/repair any brittle or burnt connections, put shielding on where missing, and clean the connections well before you buy a harness.

Some wrist grease (its not as tough as elbow) and a multimeter, and a few hours, and you might just find your bike works a treat-

Hm I'll have to check in person on that shielding when I get home tonight. I'm thinking of getting a regulator/rectifier combo to knock out some of the dirty pieces here. That should also replace some of my connections.

Yeah Riff, you got some cleanin' to do. 

How does your fuse holder look...front and back.

Haha yeeeeah it's pretty gross.

I bought a brand new fuse holder from HondaMan to get blades, so that's the one clean part.

Think it's salvagable?

Yeah, i think so...polish all those connectors.  I wrapped a few qtips in 0000 steel wool.  took some time but its worth it.
Gently squeeze the female bullet ones so the fit is tight, add dielectric grease.
The block connectors are tough because the plastic turns brittle.  Clean them as best you can.

[Bankerdanny]

Fortunately you can order replacement block connectors and the internal connectors from Vintage connections. They also sell a tool that makes removing the existing connectors from the block pretty easy if you want to save them.

The connector between the yellow wires out from the generator to the regulator are a known weak spot on the early Goldwings. I replaces the block and bullet connectors and they still melted. In the end I soldered those wires together because you rarely need to remove them.

[riffman12]

OK cool I'll get to cleaning and replace connectors as necessary.

You guys think my charging problem lies in this acid mess?

I'm gonna be pissed if I clean all this and it's still there haha

[flybox1]

OK cool I'll get to cleaning and replace connectors as necessary.

You guys think my charging problem lies in this acid mess?

I'm gonna be pissed if I clean all this and it's still there haha

This is just one bump in troubleshooting process.  It should be done anyway because of the possible acid spill.
If the problem persists, at least you know you've made progress towards finding it. 

[riffman12]

ok quick update. I got some time to do some cleaning and testing this evening. I used this guide as it seemed pretty detailed:

http://www.hondachopper.com/garage/troubleshooting_charging_system/troubleshooting_charging_system.pdf


Stator:

I measured resistance between the 3 yellow wires coming from the stator. I got 0.7 ohms for each of the 3 combinations. The guide says it should be 0.2. Is 0.7 high enough to indicate a bad stator?


Rectifier:

I'm a bit confused here. I have the rectifier out of the bike and sitting on a table. As the guide stated, I put the red lead from my multimeter on one of the yellow wires, and the other on the red wire. The guide says it doesn't matter what the reading is, but that they should all be the same. I am not getting any reading from any of the yellow wire combinations.

I'm also not getting any readings in the opposite direction.

I'm also not getting any readings when I put the red on the ground, and the black on any of the 3 yellow wires.

Is my unit bad? Or is my multimeter not putting out enough voltage to test this properly?


Regulator:

my resistance across the black and white terminals is 0.4. Apparently this number is supposed to be zero. Is that correct?


Thanks and sorry for all the info. This stuff is very alien to me 

[riffman12]

One more piece of info. My field coil is measuring 7.7 ohms. That guide says it should be 7.2.

Thanks guys

[Jerry Rxman Griffin aka MuthaF'er]

You are off by 0.5ohms on the field coil as well as the stator leads. That 0.5ohm difference may be your meter. What does your meter read if you touch both leads together? The stator pairs are all the same. I'd say you are good on both PROBABLY.

The rectifier is designed to produce DC from AC by eliminating one half of the alternating current thus leaving you with non-alternating direct current. You should have flow in one direction only. You are testing for continuity here, NOT ohms. Is your meter set accordingly? Continuity in one direction is expected. Both directions, or neither direction, it's shot. Make damn sure the center post has a good clean ground between the threads and the frame!   

Can't say about the way you are testing the regulator?? It WILL have resistance IMO. There is a coil inside there and points. Anyone??

If you still have doubts about the reg and rect you can always dump a hundred bucks on a solid state combo unit which COULD be considered an upgrade but it may not make much of a real difference.

Without going back through all this post have you metered you ignition switch for resistance/voltage in and out? 

[riffman12]

You are off by 0.5ohms on the field coil as well as the stator leads. That 0.5ohm difference may be your meter. What does your meter read if you touch both leads together? The stator pairs are all the same. I'd say you are good on both PROBABLY.

The rectifier is designed to produce DC from AC by eliminating one half of the alternating current thus leaving you with non-alternating direct current. You should have flow in one direction only. You are testing for continuity here, NOT ohms. Is your meter set accordingly? Continuity in one direction is expected. Both directions, or neither direction, it's shot. Make damn sure the center post has a good clean ground between the threads and the frame!   

Can't say about the way you are testing the regulator?? It WILL have resistance IMO. There is a coil inside there and points. Anyone??

If you still have doubts about the reg and rect you can always dump a hundred bucks on a solid state combo unit which COULD be considered an upgrade but it may not make much of a real difference.

Without going back through all this post have you metered you ignition switch for resistance/voltage in and out?

That's an interesting point. I didn't even realize everything was off by .5 ohms. What's strange is when i touch the ends of the meter together it only reads 0.1 or 0.2

As for the rectifier, I thought you could test them by measuring resistance in each direction (it should only be in one direction). Either way, when I put the meter on continuity / beep test, I couldn't get it go beep with any combination of the leads coming out of the unit. That seems odd to me...

I haven't tested the ignition switch yet. I have the whole electrical panel out of the bike and I am testing each unit individually.

Is the ignition switch a common failure for the charging system? I believe the PO said he replaced it. How would I test it?

[Jerry Rxman Griffin aka MuthaF'er]

If you are not getting CONTINUITY (not resistance) in either direction on your rectifier it is toast.

The ignition switch runs a large flow through it. Aftermarket, as Cal says, are notorious for failing and 40 year old Honda switches should also be suspect.

[riffman12]

hm alright I'll check out the ignition switch this evening. The PO actually replaced it with a factory unit - I assume off ebay or something. Perhaps that's bad too.

But it sounds like either way, I should replace my rectifier. I've been researching the best aftermarket replacement but there seems to be a lot of mixed info.

Anyone have a suggestion? I've seen the Ricks combined unit as well as electrosport. Then the Oregon vintage unit is a bit more expensive. Are all of these plug and play? Do they mount easily to the factory electric panel?

[Jerry Rxman Griffin aka MuthaF'er]

Bunch of good COMBO units out there. Mine is Electrosport on my original bike and unproven stock set up on Son of Original so far. Pretty much plug and play. Remove the stock regulator AND rectifier. You will probably have to fab a mount across the holes for your original regulator (not sure about non-Electrosport). I used a 1" width piece of aluminum stock from the hardware store to bridge the 2 regulator holes, used one of these to attach the aluminum bar and the unit and drilled a third hole between for the second hole of the unit.

Look at the manual and double check your continuity to be sure you checked your rectifier correctly. Also you can destroy them if tested incorrectly. 

As far as 'factory units' finding a NOS switch is like finding hen's teeth. Damn near non-existent so that's suspect unless he used a used unit which is then also suspect. Any of the F's switches will work even though the part numbers are different. The difference is in the seat lock in the set. The 75/76 has the spring loaded cover and the 77/78 does not. A after-market replacement base is available but will not work with the early 75 switches as it's connectors are positioned differently. That may be your best solution if you have a decreased voltage coming out. Don't need to replace the whole switch. Not great quality but it'll be new and probably better than what you have.

     

[riffman12]

cool thanks again guys. I just ordered a Rick's combo unit because it was on Amazon Prime, had good reviews.

I also forgot to mention that I have an H4 headlight on the bike now. Could that be causing some of my issues?

As for the seat lock, I cut that off long ago. 

I'll try and test the ignition switch tonight

[Jerry Rxman Griffin aka MuthaF'er]

The H4 is an added draw. I have that and also 3 ohm coils. Combined bigger draw but a healthy system should support it the H4. I had issues before with maybe 13V at best but after I replaced EVERYTHING I tested the system at first start up and got the holy grail 14.5V.

[riffman12]

OK quick update. I received and installed my Ricks reg / rec combo and I think everything's in correctly.

The instructions that came with the unit made it clear that all the connections must be clean to stop any hang ups, and even singled out the ingition switch as the most common choke point.

They said the best way to test the system is to check for voltage drop. Their instructions are:

1) disconnect the new reg / rec box from the system

2) measure voltage across the battery terminals, note voltage

3) measure voltage from the positive on the battry, to the harness side black wire that plugs into the regulator, note voltage

4) if there is more than a 0.4 V drop between the 2, it means there's a bad connection somewhere in the system (maybe even the ignition switch)


After cleaning all my connectors, I performed this test and got a 0.01 V difference between the two readings. Does this mean my connections including the ignition switch are all good? Or is that too good to be true?

I haven't had a chance to test the voltages at different RPM as it's a bit late to run the bike. I'm also now having issues getting the bike to run smoothly, see here:

http://forums.sohc4.net/index.php/topic,158253.0.html

I'll report back once I can get the bike to run properly and test revs.

[riffman12]

yeah I thought it seemed too good to be true. Is that the correct way to test the voltage drop of the system?

1) measure across battery terminals with key to ON position (black to neg, red to pos) - note that voltage

2) keep the red on the positive battery terminal and put the black on the black regulator wire coming from the harness - note voltage

or am I doing that wrong?

[Jerry Rxman Griffin aka MuthaF'er]

So what is your system voltage at the different rpm levels with the new unit??

"and even singled out the ingition switch as the most common choke point"

I'm not an electronics whiz by any means but..... check the switch output if the r/r didn't solve your problem?!

[riffman12]

going to check the different RPM levels this evening if I can get my fuel lines sorted out. At the moment I'm not getting even fuel flow and the bike won't hold idle so I can't test the voltage.

[b52bombardier1]

Don't forget to check for the presence of AC at the battery. If you are already set up for the DC volts check then it's an easy knob flip on your multimeter to the AC volts setting.

 Hope for less than a half a volt AC at half throttle or so. Much more indicates a failing rectifier.

Rick

Sent from my SAMSUNG-SM-N900A using Tapatalk

[riffman12]

OK guys... I think you were right about the ignition switch.

Installed my new rec / reg combo and here are my RPM results:

1000: 12.2V

2000: 12.6V

3000: 13.1V

4000: 13.6V



So it looks like my issue is still there. Then I went and tested the ignition switch. Let me know if this is correct:


1) Key off, I put my black probe on the neg battery terminal, red probe on the red wire at the fuse box

2) Key to position 1, black probe on neg battery, red probe on black wire at fuse box

3) Key to position 2, black probe on neg battery, red probe on brown wire at fuse box



here's my results:

battery voltage ignition off: 12.6 V

battery voltage ignition on: 12.2 V

red wire at fuse box: 12.57 V

black wire at fuse box: 10.95 or 11.1 depending which side of the fuse box

brown wire at fuse box: zero



My position 3 has never actually done anything now that I think of it... What is it supposed to do?

Am I right in thinking the culprit is my ignition switch? What's my best plan of action here? Replace it or rebuild it?

[riffman12]

hm but if I'm measuring 12 .2 across the battery and only ~11 through the switch, isn't that sucking up a lot of voltage?

The 3rd key position has never worked since I bought the bike. That plus the voltage drop makes me suspicious of the switch.

The fuse box is brand new from HondaMan so I don't think that's the issue.


Some of my measurements might be kinda odd because I'm new to all this wiring stuff and have no idea where to stick the meter probes haha. I stuck the red probe inside the plastic block connector where the fuse box connects to the harness...is that a good spot to test the switch? I'm not sure where else to test the wires coming out of it.

[riffman12]

checked the fuse block. There is continuity across all 3 fuses.

Here's a pic of my fuse block. This is where I was sticking the red probe to test the ignition switch




Here's how the reg/rec combo is wired:




It plugs into the normal block connector that plugged into original rectifier. Then the 3 skinny wires plug into where the original regulator spade connectors did

[riffman12]

as a way to rule out the ignition switch, could I just remove / bypass it (hot wire the bike basically), and then do an RPM voltage test?

Then if my readings are good I know it's the switch, right?

[riffman12]

ok thanks

the only part that I'm a little lost on is "Count the # of DIFFERENT wire COLORS coming from the RR."

My new reg/rec combo unit has a block connector as well as 3 separate wires. Do I go down the "4 or less" arrow saying that our bikes have a permanent magnet alternator system?

[Jerry Rxman Griffin aka MuthaF'er]

Yeah, your magnet is not permanent. It is made up of your stator and field coil and is only working when the crank is turning and there is voltage going to the field coil to 'excite the field'.