Topic: Advice?

[Ebrandon]

I have a 81 CB650c. I replaced the battery last week and enjoyed a few days of riding, but now my bike won't start. When I hit the starter it dims the lights and makes a click and then nothings. No cranking, nothing turning over, nada. Of course this bike doesn't have a kick start. So I basically have two questions:

1. How do I know if the starter is bad, and is it easy to replace? (I like to do thing myself, but don't want to et in over my head.)

2. If it is the battery, what could be causing it to lose it's charge so quickly? The shop I bought the battery from charged it fully before I got it.

Any help is appreciated.

[SteveD CB500F]

The click plus dimming lights is a sure sign of a flat battery.  Which means that oyur charging system is not working.

Charge the battery overnight and then measure the voltage across the terminals:

1. Ignition off
2. Tickover
3. 2000rpm
4. 3000rpm

etc

Post back.

[csendker]

Sounds like either a short or poor charging.  

Short test: Pull the negative wire see if there's any voltage or current running between the wire and ground with everything turned off.  If so, it's a short.  A small test-light works wonders here.  

Charging: Check the voltage while running the bike.  You're manual should give the voltage-to-RPM curve.  For the 550, it's something like 14.? volts when over 2-3,000 RPM (working from memory here).

Once you've figured out which it is, then you can start to track it down further.  Of course, it could be a bum battery too.

[Ebrandon]

Thanks guys!

I will give this a try and let you know what I find.

[dusterdude]

or you have a drain.

[Ebrandon]

Well I tested the battery and it was at 11.5 volts. Once I had the bike running I tested it at different rpms and the meter never moved- so it is definately not recharging. I think i am going to replace the regulator/refrator, it seems the most likely candidates since the bike has been jumped off in the past. Luckily I know someone who can get their hands on an after market piece for pretty cheap, and i sounds like I should be able to replace it myself with no problem. I am so happy, a local shop about had me convinced I needed about $200 in parts, plus labor. ugh!

Thanks for the help!

[SteveD CB500F]

Before you start replacing parts, check the output of the alternator (don't forget that it's AC).

If there's no output, check the primary as the primary windings have to be energised for the alternator to work.

[TwoTired]

Before you start replacing parts, check the output of the alternator (don't forget that it's AC).

If there's no output, check the primary as the primary windings have to be energised for the alternator to work.

I thought the Cb650 had a Permanent Magnet type alternator with slip rings (brushes)?  This would mean it is self excited.  And, if the brushes were worn to the point of no contact, no output.

Of course, you can just keep replacing parts until it works again.  But, you've got a meter to probe with.  Why not use it?

I have no documentation on the CB650.  So, its charging system specifics elude me.  Is there an online source?

good luck!

[SteveD CB500F]

Sorry - forgot that it was a 650   

[byidesign]

I have a cb650sc "82} the 81 is the same , you do have an alternator with brushes. mine
   needed replacing by 25,000 miles How many miles on the bike?
       with the ignition off there should be no drain on the battery.{disconnect one cable,from battery} after fully charging it.
          and hook a 12v. test light between them ,see if it lights,
        if there is , pull the connecter{s} off the rectifier/ regulator, and see if the
       pull{drain} on the battery stops, if so check the diodes{faulty reg.} {see faq's} or
        a shop manual on proceedures ,someone here,may have that already up on the
        site.
           post what you find out.
           Hope it helps
                    Bruce

                         
 

[Ebrandon]

What's the easiest way to check the output of the altenator?

The bike has around 10,000 miles, but it sounds like it wouldn't hurt to check the brushes.

I will give a look at those things.

Once again thanks!