1978 CB550 not charging

[john83]

First off, yes I know there are a bunch of threads related to this but so far I haven't found one that helps solve my problem.

Second off, this my bike does not have a stock wiring harness. PO rewired the whole bike and installed a solid state R/R.

The bike will crank and run but doesn't seem to be charging the battery. I know the battery is good because I just replaced it. I use a trickle charger to charge it up and I'm starting with a battery reading of 12.8V, or somehwhere in there. Volt meter across the battery terminal at idle basically only reads battery voltage, 12 volts or sometimes less if I've been messing with it and the battery has dropped down below 12. Revving has little or no effect, voltage might go up a tenth or so but nothing significant. I've looked a ton of troubleshooting guides and checked the following.

There is continuity between all three phases of the stator, about 1.5 ohms.
The field winding has continuity, about 5.5 ohms.
Tested the diodes in the R/R according to the troubleshooting guide and they checked out.
There is AC voltage coming from all three phases, about 10V but that doesn't change when I raise the RPM.
I've looked through the wiring and can't find any loose/corroded connections, burnt wires or anything of that nature.

I'm a little unsure where to go now. I've seen some mention of bypassing the regulator and sending battery voltage straight to the field winding but not quite sure how to do this.

Anyone got any other ideas? What should the AC output voltage be, 10V seems a little low?

 

[john83]

Update. Just on a whim I went out and tested it with the headlight turned off, got high about 12.8V at idle and over 13 at higher RPM. Tried it with no lights on, closer to 13V at idle and over 13.5 at higher RPM. I did replace my headlight bulb recently, could I have replaced it with one of too high a wattage? Is the stator to weak to run lights and charge? Confused.

 

[Bozz]

This is the money quote"There is AC voltage coming from all three phases, about 10V but that doesn't change when I raise the RPM."

You should have more than 10VAC across the stator wires, with RPM it should be above 12.
If it was a permanent magnet rotor system you would be getting upwards of 20VAC.
Something is not right with your Rotor/RR/Stator.
Check Rotor Brushes first, IMO. They are a mechanical wear point and are cheap to boot.

 

[john83]

Doesn't have brushes. It's a two part "rotor" the part with the wiring is actually stationary and magnetizes the part that spins. See attached schematic.

Forgot to mention that the stator was replaced about a year and a half ago with a NOS honda part. So could that have gone bad or perhaps the field coil is going?

 

[Bert Jan]

The three yellow wires coming out of the rotor are giving waaay more then 10v~
You should get about 30v~ between either one.

The problem could be your meter. Newer multimeters can have a hard time checking ac, because it fluctuates too fast and the lcd on the meter cant keep up.

My guess is that your field coil is not getting anything. The cb550 has a field coil system. This means that in order to give power, it needs power. Basicly its a magnet wich generates power. The smallest coil (white and black wire) gets power from the RR. The RR knows how much it needs because the RR measures the voltage on the bike. If its too low, the RR gives some power FROM the battery to the field coil. The rotor gets more magnetic, thus delivers more voltage, eliminating the voltage shortage. If the RR registrates too much voltage on the bike, it will lower the power to the field coil, thus lowering the magnetic field and voltage coming from the rotor. The diffrence in voltage goes to the battery for loading and/or dissapates to heat (hence the ribs on the RR.

My guess is that your field coil gets no power. No power in is no power out.
Quick n dirty way is to put power on field coil wires and check if the three yellows give more then the 10v~.

Report findings please, we're here to help!

 

[Bozz]

Right, what Bert said.
The honda models run together in my head sometimes. Certain models had brushes, others do not.
So we are both saying the same things, it's just that Bert is using the right words!


Field Coil/Rotor is still my first suspect.
Bert's test will tell you if it's the Field Coil or the RR.

 

[john83]

Quick n dirty way is to put power on field coil wires and check if the three yellows give more then the 10v~.

Report findings please, we're here to help!

I did make an attempt at this earlier but not sure if I did it right at all so didn't include it in my findings. Coming from the stator I've got a block connector with three yellow wires and a green, I know these are the three phases and ground. I've also got a single white wire that connects to the R/R, I believe this is the field coil power wire. I unplugged the white wire and ran a jumper wire from it to the positive battery terminal. I then started the bike and checked AC output voltage but had no noticeable change. I wasn't sure if this was because the field coil wasn't working or because I conducted the test wrong.

 

[Bert Jan]

Black wire on honda's is switched positive. That means that all black wires are hot as soon as the ingnition is set to the "on" position.

What you did was put a positive on both wires coming from the stator. I'm not sure if that can cause instant damage.

Set the igniton in the "on" position and check for power on the black wire coming out of the RR with all plugs connected. If you have full power on the black wire coming out, its ok. If you have no power, your RR is bad.

The reason both red and black go into the RR is that the RR needs to calculate the difference between them. Black needs to be the same as red. But because coils and light comsume power from the black wire there is s difference. The RR compensates that difference by giving the stator more or less power.

You see, it all works together and when one part breaks it can be kinda hard to find the cause. I can only tell you how it is supposed to work. You have to find out why yours isn't doing what it is supposed to do.

Stay on it, stay systematic and read yourself into the wire shizzle. It is not that hard once you understand what every magic box does

Again, report findings!

As far as i can see it from here my money is on either the RR or stator. Putting power on both stator wires should have given fireworks. The bad kind.

Measure continuity thru stator!

 

[john83]

Isn't the white wire 'going to' the stator. By which I mean it sends takes power to the field coil, right? By putting battery power directly to it, didn't I just bypass the regulator? Shouldn't that have allowed the field coil to produce as much magnetism as it can? Shouldn't that have increased AC voltage?

 

[Bert Jan]

Well, in theory it should. But as black wires are always hot on honda i think the white is the return wire. The regulator gives via the black wire.

 

[Sonreir]

Well, in theory it should. But as black wires are always hot on honda i think the white is the return wire. The regulator gives via the black wire.

That's only with the DOHCs. On SOHC, the white wire is positive and a green wire leads from the exciter to ground. No harm in putting 12V to the white wire other than the possibility of generating too much voltage for the system.

 

[john83]

Okay, that's what I thought. I didn't think I was that bad at reading wiring diagrams. So if I put 12V on the field coil and didn't get an increase in voltage does that mean it's going bad?

 

[Sonreir]

While the bike was running?

 

[john83]

Correct.

 

[Sonreir]

Possible, but not necessarily. Depends on your revs.

I'd check it with the engine not running. Put 12V on the white wire and if the rotor can hold a 14mm wrench, you're probably OK.

 

[john83]

Haven't done the magnet check yet. I don't have a stator cover gasket and didn't want to remove the cover till I had to. Interesting new development though. Fired the bike up today and put the meter on it, 14V at idle. Then when revved it went over 15V. Turn the headlight on and voltage starts dropping below 13 in a hurry. Turn the headlight back on and and it registers about 13V at idle and picks up to nearly 14 at higher RPM. Turn engine off, restart engine and we're back to over 14V at idle.

All these voltage readings bouncing around makes me feel like it's a R/R problem. Am I way off base?

 

[john83]

Well, the R/R fried itself. While the bike was shut off and in my shed. Odd but I believe that narrows it down a bit. Soon as parts arrive I'll do some looking to make sure that was it.

 

[_millmo]

So it was the rr? Even tho it was holding charge with the light off? The same is happening to my cb550 with a headlight from China.

 

[john83]

I never did get it charging very well. It's in a bunch of pieces right now while I cafe it. Hopefully I'll get it better when I put it back together.