1982 Honda CB 650 -- Electrical / Charging problems (as usual)

 Hello everyone, so I just bought a 1982 Honda CB 650, although I
overpaid a bit for it, due to my huge desire to have a bike to ride
this year... I ride it home, but on the way it starts dying.

I've been reading all about the electrical and charging issues these
old Honda's have. I've heard all sorts of replies. I started checking
what the problem is, I ordered the Haynes repair manual, which should
be hear soon, but in the meantime I want to know:

In this particular model, if everything is working good, if you
disconnect the battery while the bike is running, will the bike die or
not? On newer bikes it doesnt die, but i'm not sure for this model,
because mine definately dies immediately.

I checked the voltage yesterday while the bike is running, and
reving... 8 volts or so, I took off the stator cover and sprayed
electrical parts cleaner and used some high grit sanding paper to clean
off the stator/coils... now when i'm running the engine its at about
12. I know I need about 13-14v to successfully be charging the battery.

Any ideas? I mean... something changed. Possibly a loose connection
somewhere or high resistance somewhere? I am thinking of sodering
anything that looks suspect. What wires should I soder, which wires
shouldnt I?

And if it comes down to it, where would I buy stator/coils/etc for it,
aftermarket or OEM?

 ben@spidre.com wrote:

Carefully follow the instructions at

http://www.electrosport.com/electrosport_fault_finding.html

It's a very, very good start.

bob prohaska

 
ben@spidre.com wrote:


I really doubt that you sanded the enamel insulation off the stator
coils. That would be a very expensive less in what not to do.
Alternator stators have only enamel for insulation, if you pierce the
enamel, the coils short out to each other.

I think you may be talking about slip rings on the alternator rotor?
Does that alternator have carbon brushes? When brushes wear out and get
short, there isn't enough spring pressure to push the brushes against
the slip rings hard enough to make good contact. So there is high
resistance and the excitation current to the rotating electromagnatic
field is reduced.

How many wires go to the alternator, three or five? A three wire
alternator has an external permanent magnet rotor and the voltage
regulator simply rectifies AC current and shunts excess current to
ground to be burned up as hear.

But the five wire alternator will either have brushes or it is a
brushless type that Kawasaki and Honda used. That type is what is
called an "excited field" alternator.

The regulator will have a large power transistor that passes full
battery voltage to the
alternator rotor until the voltage reaches a certain level. Then the
transistor stops passing voltage. The transistor is ON or OFF, nothing
in between.

Charging voltage tests are done with a fully charged battery that is in
good condition

When you increase RPM, the voltage should rise to something like 14.5to
15.5 volts at 5000 to 6000 RPM, then you should see a sharp decrease in
voltage. It's best to use an analog voltmeter with a needle instead of
using a digital meter that takes its own sweet time counting
millivolts.

When you decrease the RPM, the transistor should turn ON again and the
voltage should rise and fall noticeably as you cross and recross the
RPM at which rising voltage triggers the transistor.

now when i'm running the engine its at about

That tends to indicate the battery plates are sulfated. Sulfation is a
normal process that takes place when a battery is discharged. Lead
sulfate forms on the spongy lead plates and charging current from the
alternator or a battery charger cannot penetrate the lead sulfate
layer. All that the battery can accept is a "surface charge" on the
plates.

Motorcycle alternators are not very powerful, compared to a car
alternator. A motorcycle alternator cannot raise the voltage of a badly
discharged or sulfated battery, all it can do is boil the water in the
battery.

Motorcyclists think that they are doing their battery a favor if they
keep adding water as the level lowers. Water has a lower specific
gravity than electrolyte, which is a 50/50 mix of water and sulfuric
acid.

The normal chemistry of a battery takes the sulfur out of the
electrolyte and attaches it to the spongy lead plates. The remaining
electrolyte is mostly water, which doesn't conduct electricity that
well. All the alternator can do is boil the water out of the battery.
So, if your battery seems to always need water, chances are the plates
are sulfated, and it will only get worse, because the alternator simply
cannot charge the battery and neither can a battery charger.

Look for connections coming out of the alternator that have insulation
that is turning brown or black. Also, look for the two DC outputs from
the regulator for burned or blackened connections. Coonections that
have burned and blackened are poor conductors of electricity, they burn
it up as heat instead.

Also, some Hondas with shunt-type have a remote DC sensing wirethat
goes up to the instrument panel, instead of sensing voltage directly
off the battery. I don't think you have that type of permanent
magnet/shunt regulator though.

Also, check your engine-to-chassis ground cable and look for bad ground
connections  from the voltage regulator to the chassis if your machine
has to use a chassis ground instead of a ground wire.

Check with Electrosport USA.

 
ben@spidre.com wrote:

You ought to start by making sure the battery is good.
Sounds like you already have a multimeter. Charge the
battery with a charger and test the voltage. A good shop
can also test the specific gravity and/or load drop and will
do this as a courtesy as part of selling  new batteries.


I really wouldn't do that unless I had some clue what I was doing.
Wait for a manual and understand it before breaking out a soldering
iron. I don't think there's going to be anything to solder.

If you want something useful to do while you're waiting for the
manual, one by one, disconnect, clean, then reconnect the
wires in the charging system. Make sure you only have one
or two off at a time and know where to reconnect them.
It wouldn't be unheard of to have crapped up battery cables
and/or bad grounds.

After you're sure you've got a good battery retry your voltage
tests. Not sure about your bike but mine starts charging at
about 1500 RPM. Below that, there's a slight discharge
of the battery.


I'd start with Eletrexusa.com

 
Rob Kleinschmidt wrote:


A sulfated battery will charge up to the recommended voltage and the
specific gravity will show the battery is fully charged while it
actually only has a surface charge on the
plates. It will fail the capacity test.

All that's necessary to do the capacity test is to hook a motorcycle
headlamp across the battery terminals. A 55-watt headlamp will draw 4.6
amperes.

If the battery in question is a brand new fully charged 12 ampere hour
battery, it should light the headlamp for 12 / 4.6 = 2.6 hours without
the voltage dropping below 12 volts.