Topic: Charging System (Again, Again, Again...) Advice

[c_kyle]

1979 CB650

My charging system is not working.  I have a new battery and the regulator/rectifier has been replaced recently.  I've read through some of the Charging System troubleshooting guides and they look fairly complicated.  To make things worse, the dealership told me they didn't work on anything that old.  There is a local shop that specialized in vintage Japanese bikes, but the shop is a complete mess and the guy seems like he's out to rip people off; that's just my impression, which may be completely wrong.  I'm not sure I can sucessfully test the charging system myself, it seems complicated.  The shop charges $50 to diagnose the problem, which sounds reasonable, but who knows if they're going to check everything that's listed in the troubleshooting guides.

[Jerry Rxman Griffin aka MuthaF'er]

Get a wiring schematic if you don't have one. You're going to also need a cold 6 pack for this daylong project. Chase down EVERY connection. Take them apart whether a bullet connector or spade connector and clean BOTH sides. Pull the spade connectors out when you do this. Put them back together and use dielectric grease. See if it's charging at this point. I know this is a real pain in the ass but if you really want to ride your 28 year old bike it needs to be done once every 28 years! If this doesn't do the trick then we can tell you how to check the individual components. Don't, and I repeat Don't, cheap out and not do this part first. There's only about a million of us that will attest to this!   

[c_kyle]

What is the recommended repair manual?

[DammitDan]

Go for Clymer.  It's step-by-step and more "Mechanics for Dummies" than Haynes, IMO.

And of course you can't go wrong with a good Honda shop manual.  There should be some PDFs floating around the site if you can find a link to it.

[c_kyle]

I found a wiring diagram from oldmanhonda.com.  I'll order one of the Clymer manuals; I wasn't sure if the Clymer or the Haynes was the better manual.

[Jerry Rxman Griffin aka MuthaF'er]

Clymer, Chilton, Haynes are all better than nothing thats for sure. They all are somewhat incomplete and have some errors. I have 2 due to this PLUS a Honda shop manual which I should have gotten first and saved the $$ on my other manuals. I'd spend a little extra and get the shop manual. Honda uses Helm to provide the manuals. 1-888-292-5393 or www.helminc.com.

[TwoTired]

To troubleshoot your charging system directly, I'd highly recommend you get and accurate digital multimeter capable of measuring small values of Ohms resistance.  You don't have to spend a lot.  A $30 meter from Harbor Freight will do the job.  And, they aften have sale price reductions on these for as little as $3 (which is kind of funny as they sell the testleads that are included with this meter elsewhere for $2) . 
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90899
Here is an armored one to survive physical abuse:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=37772

We can walk you through what to measure and how to find the errant component.

I've helped a couple 650 owners in the past with this.  You may be lucky and only need to replace the slip ring brushes in the alternator,  But if the resitance of the rotor isn't somewhere near the value of 7 ohms, you will have to replace the rotor.

Also, you must test the charging system voltages with a fully charged battery.  So, get yourself an automatic battery tender such as the Yuasa  Smartshot 900 to get your battery to full charge.
http://www.partsmag.com/0404/Yuasa-0404/Yuasa-0404.html

If you want to cheap out, here is an unknown quality automatic charger for $8.  But, I don't have direct experience with it.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=42292


You can spend far less than $50 to diagnose the system yourself, plus gain knowledge about your bike and how it works.  But, if you don't like to or don't want to work on your own bike, then pay to have it repaired.

Cheers,

[mack808]

650s use a similar set-up to the DOHC 750s, in that they have commuter brushes rubbing against the center rotor. Either the brushes may have worn out or the rotor has failed, and this was very common with this set-up. The rotor, if you can find one is horrendously expensive, but maybe with luck you just need the brushes......  Good Luck