Electrical question

Thanks. I am admittedly ignorant of bike electrics but nowhere near stupid.
I have had over 40 years of experience with bikes and have never had this
type of problem. In spite of your expertise, which I am at a level that I
respect, there is a real world where no matter how much research and
technical data one has to work with, a solution can be allusive when
findings do not match the data exectly. For example, when I measured the
resistance between the various wirings, the rotor rings, etc. I got all
kinds of crazy readings all over the place that corresponded with nothing I
could interpret from the Troubleshooter or manual.There are artists with
bikes as well as engineers -- I could go on about the mechanic who says to
"touch the rectifier--if it is hot it is working, if cold it isn't" --that
is the kind of knowledge that will help me with this problem out here in the
boonies, a mechanic's approach. If you can tell me what a bad rotor might
look like, or feel like, or smell like -- now THAT would be helpful. All I
asked was if I swapped a good reg/rect and it burned out, what would be the
likely cause -- because I was given one that was of questionable worth, but
I thought the answer may provide a clue.

Pflu

Pflu

 

Oh, for *****'s sake*.

A crankshaft spinning, while the rotor on the end isn't, is going to
make a noise so horrendous it might even penetrate your skull.

(Some Ducatis are known to have suffered this ailment)

 

You mean, like me telling him it's 10:1 it's the reg/rec, while you
suggest that the crank is spinning but the alternator isn't?

Good call.....

 

When he says that, he is almost certainly *right*.

Reg/recs fail relatively frequently. Alterators don't. That is to say,
they fail but nowhere near as frequently.

In fact, in 32 years of biking, and ownership of roughly 300
motorcycles, I've had *one* alternator fail. I've seen half a dozen
fritzed reg/recs, though.

 

I only just found this group a week or so ago. I will be quick to offer any
help I can provide. Ask me something about patching a carb diaphragm in the
mountains and I can help -- ask about the diameter of one of the jets and
there is no sense in my responding just to say I don't know -- not that that
would stop a lot of others from posting responses just to read how cute they
can try to be.

So far this is the second question I have asked but it is follow-up to the
first. The first responses to both of my queries were bullshit -- and I
answered back with bullshit. Given the choice, I don't usually frequent
places where most of the dialogue is mean-spirited in my daily life, why
would I want to put up with that on a regular basis here? Not a source of
fun for me.

I come here for information and will gladly offer information about
motorcycles to anyone I think I can help.

Pflu

 

Erm, no.

 

OK, when you say the charging system is not working what are the symptoms?
Did you rule out the battery itself? Swapped with a known good one or
checked the electrolyte in each cell?
Are the rest of the electricals working? Lights, etc.
Do they work when the engine is off (assuming that there is juice in the
battery for this)
What sort of measurements were you able to do with the alternator? I
suspect that most resistance measurements look very much like a short
circuit (less than 2 ohms)
Are there any fuses between the regulator and the rest of the electrics?
Check to see if it is blown?
In general you have the AC source (alternator) the rectifier and a
regulator. Everything else is a load on the system. If you use the ohmeter
on the output side of the regulator and measure towards the battery (remove
the hot lug on the battery before you try this!) what sort of measurement do
you get? 100's of ohms? 10's of ohms? Less than 2 ohms? You could have a
shorted harness that pulls too much out of the regulator and blows it out.

This is a generalized list of questions because I don't know what you have
tried so far and don't know that specific system that you are trying to fix.

 

I've had alternator rotors come loose on two different motorcycles.

 

Wrong. When my GS1100's alternator stopped turning with the
crankshaft, it made no noise at all. When my Yamaha's alternator rotor
stopped spinning, the engine wouldn't run at all because the
alternator rotor wasn't exciting the stator coils to make voltage for
the coils.

 

OK. Ducati's make a horrible din. So do MZs. It's still highly unlikel;y
to be the problem here.

 

That's because they had you as a 'fixer-upper'.

 

Yeowsa!

First, start digging in groups.google.com's archives since this issue was
covered here about a month ago - I should know as I was the instigator.

If you can't do this here are the highlights, ASSUMING your CB650
uses the same charging system as my CB750

1) Your rotor is friction-fit on the crank shaft. There is no key. If
for some insane reason the rotor bolt came loose (perhaps the head
snapped off or some such) and the rotor itself came loose (very
difficult since the setting force is something like 50ft pounds of torque
and even after the rotor bolt is removed the rotor isn't coming off
without a puller) then you could easily have the rotor NOT TURNING
when the crank was turning. And it would not make any noise. Sure,
if a key was there it might. But a key isn't there. And frankly if that
did happen, it would likely gall the crank snout and the rotor would
-never again- friction-mount to the shaft properly.

2) Your rotor has 2 slip rings on it. There are 2 brushes in the housing
that push against the slip rings. The brushes are soft metal so they don't
gouge the shit out of the copper slip rings. They wear out. And when
they wear out they start bumping over the surface irregularities and
sparking,
which leaves carbon all over the sliprings. They also get hot which takes
the temper all out of the springs that push the brushes against the slip
rings.

Take the cover off the rotor. Replace the brushes and springs, they come
as a set. Polish off the sliprings until they are nice and shiny. Put
everything
back together.

3) There are 5 wires that come from the alternator. 2 from the rotor, 3
from the stator. They go to a plug. Disconnect the plug. Take some
resistance measurements. The resistance in between any 2 of the 3 stator
wires should be the same. The resistance of the rotor should not change
much when you press the starter and turn over the bike engine a few times.
You should not see resistance measurements "jumping all over the place"
You also should see infinite resistance between any of the 5 wires and
ground.

Insepct the plug. Do any wires look melted or any of the plug prongs
look overheated and discolored? Put the plug back together.

4) Make sure the battery is fully charged. Start the bike. Measure the
DC voltage at the rotor, you should see some. Measure the AC voltage
at any 2 wires from the stator. You should see voltage coming from all
3 of the stator wires.

If you see voltage going to the rotor and no voltage coming from the
stator, then put a magnetic compass near the rotor casing, you should
see the compass move. If it does then the stator windings could be
shorted. If you see no needle deflection then the rotor windings could
be bad. If you see no voltage going to the rotor then the voltage
regulator/rectifier unit could be bad, or the rotor windings could be
shorted.

Beyond that I am not sure how much more simple I can make it. And,
almost certainly, if any of the windings of any of these parts are shorted
to ground, you could fry the regulator.

When you have gone and done that, then come back and tell us
what your meter says.

Ted

 

An experienced drag racer told me the problems that were going to
happen to my 1982 GS1100, but I thought he was just angry over what he
had done to his bike in ignorance.

The stub end of the crank is ground to what is called a "Morse taper".
There is about half a degree of angle difference between the male stub
and the female
receptacle hole in the rotor. So, when they are clamped together by a
single nut or bolt, they establish an interence fit.

But the nut or bolt cannot retain the rotor if the crankshaft RPM is
rapidly increasing or decreasing.

My Suzuki's rotor hub was a somewhat softer steel than the crankshaft
stub, and, as the rotor "walked" back and forth on the stub as it
increased and decreased RPM. enough *heat* was generated to cause
minute *welds* between the hub and stub.

The welds would form and be broken by the next rapid change in RPM.

GS1100 motors were very popular with drag racers, and the alternator
rotor would loosen up and "walk" off the crankshaft stub frequently.

Suzuki's response to the loose rotor problem was to increase the
diameter of the tapered crankshaft stub.

 

Its quite possible for a shorted rectifier to burn out an alternator stator,
you'd think a burned out stator couldn't do much to a rectifier but if any
of the windings has a short to earth it can cause a loop current to flow
through one of the 3 earth side diodes and damage it - so you need to do
some basic multimeter checks before randomly swapping parts. The first check
is that all 3 windings are isolated from earth, if there's a short to earth
then the stator is scrap without any other information.

Do that and see where you go from there.

 

You are very unlucky! I have been a motorcycle mechanic for 40 years and
I have NEVER heard of someone having TWO bikes that broke there alt
drive, In fact, I have not ever seen it happen. Lots of other problems.
Worn out brushes, shorted or open rotors or stator windings, bad
diodes and cut or worn out wires. The only failed alt drive I found was
on a CBX that had a weak spring in its slipper clutch, but it was still
turning.
Bruce

 

Possibly you failed to isolate the components you were trying
to measure. For example, if you try to measure resistance across
rotor rings without isolating the brushes, you can get crazy readings
because there may be other paths for the measurement current to
take.

If you're trying to measure resistance across slip rings,
disconnect the leads to the brushes and/or put a piece of
paper between the ring and brush when you measure.

Anyway, nobody in their right mind takes back electrical or
mechanical components after the parts have been installed
unless the guy sold you a defective part to begin with. Any
shop I ever dealt with says that when you install it, it's
non-returnable. That's why I don't blindly swap parts.
When I do, I figure the new part will be kept as a spare
if the old one is still good.

 

Thus spake . () unto the assembled multitudes:

Actually, newsgroups - the unmoderated ones at least - are for *anything*.
Helping people, sharing stories, entertainment, taking the piss, anything.
They are what people make them. There are no rules, so don't try to make
your own, and use them at your own risk.

As someone who has been using newsgroups for the best part of 20 years, and
uk.rec.motorcycles.classic for around 8, I'm going to leap to TOG's defence
here. He can take the piss like the best of them and doesn't suffer fools
gladly, but the majority of his posts (and his writings as a freelance
motorcycling journalist) display a huge depth of knowledge and experience.
Ask an intelligent question and you'll almost invariably get a very
helpful answer.

It would also help if people remembered that all responses in newsgroups
are entirely voluntary and no-one has to pay for any help they get. I've
also learned from personal experience that it pays to 'lurk' in a new (i.e.
new to the lurker) newsgroup for a while before wading in with comments and
opinions, so as to get to know the 'look and feel' of the newsgroup and the
types that post to it. It's like being a new member of a club, where you
have to earn respect and acceptance. Wade in too quickly and you can
easily find yourself ostracised.

 

But "no rules" is, in itself, a rule.

As for your explanation, anyone who can't pick that up just from reading the
posts for a few days, probably won't understand your explanation either.

Anybody with the experience you claim should know that too. ;-)

 

You can get down on your knees and gobble his knob for all I care. TOG
is the bane of this group and he's annoying other readers with his
shitwit.

 

Nobody should have to explain "liberty" to adults. In the real world,
your "right" to verbally annoy other people ends with a fist in your
snot locker, so cowardly types
hang out on Usenet to talk shit.