Topic: New here New (old) bike.

[Brandotheamazing]

Hey, i'm new here, and fairly new to motorcycles (still pretty green) but have been an auto mechanic for some time now.

Picked up a 1976 CB 550f Super Sport.
not the best shape, but i'd been looking for a project.
Replaced coils yesterday, one wasn't firing at all, and one was producing very weak spark. Bike died riding to work, coasted into the lot.

Well with that said, the bike is a little rough, but it's got new tires, chain, points, plugs and now wires and coils.

Today after riding a bit I noticed the Headlight was dim, and the blinkers non operational, and the battery died, pointing towards the Gen..

Question here is, what do i plan on replacing first? rotor, stator? anything else?

-Brendan

Oh, and how do I post a picture? i'd like to show the bike I am talking about.

[bamabiker]

I believe I would check some of the major grounds first.  If they are crusty and not making good contact,  they can prevent the battery from getting a good charge even if the stator is fine.  Same thing with all the wires and contacts going to the dim lights.  If the wires and contacts aren't close to perfect you will get some significant voltage drops and dim lights.

[fmctm1sw]

I wouldn't replace anything right now.  I had a wire disconnected from my alternator that caused mine to die.  I'd look at a manual for it.  Perhaps charge the battery and look at some charging systems tests?

[TwoTired]

Fully charge the battery (off the bike) and then check the charging system health after reconnecting.
Battery voltage at rest, then...
Battery voltage at idle, 2000, 3000, 4000, 5000 rpms
Report results for next steps.

Stock headlight?  Any other electrical mods from stock?
Does the wiring from the rectifier (under the left side cover) have melted insulation?  All it takes is one extremely brief connection to reversed battery terminals to take out the wires and possibly the rectifier.

[Jerry Rxman Griffin aka MuthaF'er]

The charging system on our bikes is somewhat marginal to start with. Doesn't take much to upset them or ruin a low capacity battery.

First, will your battery hold a charge after it's fully charged without being hooked up to the bike? Trickle charge these only as they have a small capacity and you may cook it. If the answer is no, buy a new battery and go from there. Charge it before installing. If the answer is yes then check the output of your system. If it has proper output then you have an issue in the wiring. There are many connectors in our bikes. They age poorly and create resistance which decreases voltage. Clean EVERY connector, apply dielectric grease and tighten the connections. Shorts and bad grounds as mentioned are potential issues.

Not as likely to be the hardware so don't replace that stuff first.

You didn't mention what coils you used! Coils that fire vs your old coils will use more juice just as high performance coils that fire big time vs new stock coils will use more juice too. Get used to paying attention to your blinkers. They are like a volt meter. When my turn signal beeper becomes sluggish I know my voltage is dropping.

Oh yeah, welcome aboard.

edit: TT beat me to it. He types faster with all those helping hands. I yield the floor to our master, TT.

[Brandotheamazing]

Dynatec coils, Just let the bike sit for about five days with a fully charged batt. Started right up fine (keeping the bike dry helps) a friend gave me a nice cover for it, since it has to sit outside, and isn't in the best shape.

[TwoTired]

Are the coils 3 ohm or 5 ohm types?  What color are they?

[campbmic]

I just dealt with this same issue (and I'm still dealing with it) so I might be able to help you a bit, this is the way I've come to understand the charging system.

Three Phase Charging System:

#1 Regulator - Your regulator is connected to your battery via a black wire and your alternator via a white wire. The black wire is constantly sending the voltage from your battery to your regulator. When the voltage decreases to (11.5 or lower I don't know the exact voltage) the evil wizard inside the regulator gets angry. He wants more power than that. Therefore he send power to the alternator.

#2 Alternator - Your alternator is connected to the regulator via a white wire. When there is voltage in this wire the alternator turns on and produces "AC" electricity. There is a good wizard that lives in your alternator and he produces electricity from mice spinning on wheels we believe (no one knows for sure). The "AC" electricity is sent to the rectifier via three yellow wires.

#3 Rectifier - Your bike is now producing electricity. However, there is Good electricity "AC" and Evil electricity "DC". Honda motorcycles run off of evil DC electricity. So the wizard inside the rectifier converts the good AC electricity from the three yellow wires to evil DC electricity in the one red/white wire. Here is a diagram it doesn't show the wizards but just use your imagination.




Now there is a problem with one of your wizards and you have to figure out which one it is. But before that I recommend you check your battery to make sure it can charge properly. If the battery is fine and your bike's battery is still running down then you have a charging issue. I would unplug the rectifier from the wiring harness and using a multimeter see how many AC volts your alternator is producing out of the three yellow wires. If it is producing adequate AC power then its a problem with the rectifier. If its not producing any electricity then...

Disconnect the white wire from your alternator and see if it has any voltage. If it does have voltage then your alternator is most likely the problem.

[Brandotheamazing]

Still not right, confused.
So the batt holds a charge for days, no prob. Starts up rides fine. Then eventually batt dies. Then the bike sits and the batt recovers ?? It was almost stone dead yesterday, and at 11.8v today.

Yesterday I checked voltage running, realy low at 1100 rpm, at like 4.5 v.
Then steady rise in voltage with rpm, untill its about 12.5 at 5000 rpm.

What should I check, or replace? It appears to have an aftermarket rectifier, I have dybnatec coils (the green ones) and other connecters and grounds seem good.

[campbmic]

Start the bike and measure the voltage on the white wire that runs from the regulator to the alternator tell me how much voltage is in that wire and how much voltage you have at the battery terminal all while the bike is running.

[TwoTired]

If you hold the engine at 5000 RPM for a long while, like an hour or more, you'll find the battery does recharge.

I believe the green coils are 3 ohm primaries.  And that draws way more power than the stock 5 ohm types.
The stock bike does not make enough alternator power at idle to run the bike AND charge the battery, so the battery depletes at idle.  Putting in higher current draw coils just makes the problem worse and the battery drain faster.

Since you say the bike is not in the best shape, implies that all the electrical connectors on the bike are corroded.  This situation throws alternator energy out the window, making your 150w alternator behave more like a 120 watt alternator.  The stock bike normally draws about 110 watts whenever the Key switch is on, running or not.
So, I'll take a wild guess that all the connectors on your bike need cleaning, also.

Also, if there are electrical mods to the bike, well....

Finally, the stock headlight was a 40/50 Watt.  Often, when connector corrosion becomes an issue the headlight gets dimmer due to voltage loss.  So then another headlight that draws more power is installed, like a 50/65 or even higher.  If the alternator can't supply the extra power, then the battery depletes at a faster rate.