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From: chateau.murray@btinternet.com, on 10 Aug 2006 09:01

rugger81 wrote:
> I just bought an old cb750 recently and now I'm having some electrical
> problems. I was riding down the rode when all of a sudden the bike
> stalled out. I pulled over to the side of the road and I noticed all
> the electrical was out. I tried kick starting it and push starting it
> and I even got someone to try and jump start the bike but all I got was
> the power to flicker a couple of times. The battery is brand new so
> that shouldn't be the problem. I don't have the money to go take it to
> a shop and get reamed so I want to try and fix it myself. I think
> maybe the power is shorting into the frame somewhere, but I don't know.
> Anyone have any advice for me? thanks in advance.



Reluctant to state the bleedin' obvious, but have you checked the main
fuse and ascertained that you've done the battery terminals up tight?

From: FB on 10 Aug 2006 09:37

'Lefty' wrote:

> On the older bikes, where you could Switch Off the headlight during the
> day: SOME of these switches ALSO
> switched off one of the legs of the alternator. (3 down to 2).

Honda (and other manufacturers) may have done this to *protect* the
alternator from
overheating due to excesss voltage being generated during the daytime
when the lights didn't have to be on, or maybe they thought it would
save a little horsepower.

But what it tended to do was cut the alternator output in half whether
it was daytime or night time. That resulted in a lot of dead batteries
when it became mandatory to run the headlight during daylight hours.

The typical alternator has a 3-phase stator. Each phase generates about
80 or 90 volts by itself, but, since the electricity has to return to
another phase, the voltage across any two phases is 90 X 1.73 = 156
volts.

If any one of the three output phases has a bad connection, the voltage
output is dropped by half, so the stator's power output is decreased by
half.
>
> On ANY older bike thats 'brought back to life' cleaning the connections
> on all of the electrical system will get rid of
> a LOT of problems. Dirty connections cause a voltage loss/generate waste
> heat.

I use Tarn-X, a silverware cleaner that can be found in drugstores or
supermarkets. After cleaning the corrosion off the terminals, I flush
the Tarn-X off with distilled water.

Tarn-X will remove the tin plating from electrical terminals if you
leave it on too long.

Somebody else recommended a product called DeOXit that supposedly works
well.

> Better Fix: Get a Normally Open relay that will continously handle 10
> Amps of current. (120 watts)

I found a 35-amp single pole single throw toggle switch and mounted it
on a bracket on my handlebar.

> Cheap Crimp-connectors: MANY bike's wiring harnesses use these at
> connections. They Will Corrode & Open-up over time. Get Out your
> Soldering Iron, some cleaning flux, and electrical tape. SOLDER all of the
> connections you can.

The red, blue, and yellow crimp eyelet terminals you can get in auto
parts stores are especially bad. The Japanese used bullet and socket
connectors. When I replace them, I solder them on.

Motorcycles and cars and airplanes use stranded wire instead of solid
copper wire because it's flexible.

But the crimp type terminal only manages to use the outer strands of
wire where they touch the terminal metal, but soldering terminals on
makes the electricity go through ALL the strands of wire.


> P.S. IF you have a COOKED STATOR, try to re-wind the unit yourself.
> Get some transformer wire from an electrical shop, some epoxy to seal it up

Ordinary transformer wire from Radio Shack doesn't work. The enamel
insulation won't survive being bathed in hot oil. The Japanese
manufacturers used a special tough green plastic to insulate stator
wires.

From: rugger81 on 10 Aug 2006 11:30
chateau.murray(a)btinternet.com wrote:
> rugger81 wrote:
> > I just bought an old cb750 recently and now I'm having some electrical
> > problems. I was riding down the rode when all of a sudden the bike
> > stalled out. I pulled over to the side of the road and I noticed all
> > the electrical was out. I tried kick starting it and push starting it
> > and I even got someone to try and jump start the bike but all I got was
> > the power to flicker a couple of times. The battery is brand new so
> > that shouldn't be the problem. I don't have the money to go take it to
> > a shop and get reamed so I want to try and fix it myself. I think
> > maybe the power is shorting into the frame somewhere, but I don't know.
> > Anyone have any advice for me? thanks in advance.
>
>
>
> Reluctant to state the bleedin' obvious, but have you checked the main
> fuse and ascertained that you've done the battery terminals up tight?

I went over it with a voltmeter last night, and the bike was getting
power up to where it starts going under the gas tank towards the
handlebars. I took the gas tank off and gave everything under there a
good check over and wiggle test but everything looked good. I gave all
the wires up around the handle bars/behind the headlight a good wiggle
test. I checked the three fuses it has for the main, headlight,
taillight and all those were good. I just talked to my mechanic though
and he said to check the fusible link by the starter solenoid. I'll be
checking that when I go home for lunch.

thanks

From: FB on 10 Aug 2006 13:11

rugger81 wrote:

> I went over it with a voltmeter last night, and the bike was getting
> power up to where it starts going under the gas tank towards the
> handlebars. I took the gas tank off and gave everything under there a
> good check over and wiggle test but everything looked good. I gave all
> the wires up around the handle bars/behind the headlight a good wiggle
> test. I checked the three fuses it has for the main, headlight,
> taillight and all those were good. I just talked to my mechanic though
> and he said to check the fusible link by the starter solenoid. I'll be
> checking that when I go home for lunch.

Do you have 12 volts at each set of ignition points when when they are
open?

If not, check back to the + and minus terminals on the coils. Then, if
there's no power there with each set of points open, go back to the
kill switch and the ignition switch.

I'm not sure which one is first in the series, kill switch or ignition
switch on your machine.

But the ignition switch will be powered by a wire coming from the main
fuse and from the battery, and it will energize a wire that goes back
to the fuse box to power everything that works when the key is turned
on.

I have had iginition switches melt inside and have had other handlebar
switches corrode so I couldn't start the engine.

From: rugger81 on 11 Aug 2006 08:34
FB wrote:
> rugger81 wrote:
>
> > I went over it with a voltmeter last night, and the bike was getting
> > power up to where it starts going under the gas tank towards the
> > handlebars. I took the gas tank off and gave everything under there a
> > good check over and wiggle test but everything looked good. I gave all
> > the wires up around the handle bars/behind the headlight a good wiggle
> > test. I checked the three fuses it has for the main, headlight,
> > taillight and all those were good. I just talked to my mechanic though
> > and he said to check the fusible link by the starter solenoid. I'll be
> > checking that when I go home for lunch.
>
> Do you have 12 volts at each set of ignition points when when they are
> open?
>
> If not, check back to the + and minus terminals on the coils. Then, if
> there's no power there with each set of points open, go back to the
> kill switch and the ignition switch.
>
> I'm not sure which one is first in the series, kill switch or ignition
> switch on your machine.
>
> But the ignition switch will be powered by a wire coming from the main
> fuse and from the battery, and it will energize a wire that goes back
> to the fuse box to power everything that works when the key is turned
> on.
>
> I have had iginition switches melt inside and have had other handlebar
> switches corrode so I couldn't start the engine.


Thanks everybody, with your help I found the problem. The little
switch at the base of the ignition it just old and worn out. Once I
found out the ignition was getting power, I started to try and unplug
the wiring harness from the ignition. The previous owner had it zip
tied in place so after I cut those and started to giggle it out, I
started getting a power flicker. So I took out the ignition, cleaned
the connections and put everything back together, and it seems fine for
now. Just in case however, I ordered a new base to the ignition, and
will be putting it on as soon as possible. So it turns out it willd
cost me less than $20 to fix my problem.


thanks again

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