Weak charging system

[zybercom]

Hello All! Newbie here on the forums with a charging system question. I have a basically original 1980 xs650g (Special II) with a little over 10k miles on it. Recently I put it back on the road after several years storage, and it seems to run great.
Here's the problem. When my battery is fully charged my turn signals function as expected. After riding an hour or so they will light up but won't flash unless I rev the engine up close to 3000 rpm. I put the charger on overnight and I'm back in business, temporarily. I'm guessing some component in the charging system has weakened. I didn't notice a problem when before storing it. I will put a voltmeter on the battery to see what I get when revving but I'm not sure what to do next.
I really would appreciate some help. Thanks.

 

[xjwmx]

Search the site for "Curly's charging guide". Not sure of the spelling of Curley. First thing to do would be to check if you have rotor brushes. Next thing would be to check voltage at the battery while revved to 3K rpm. Should be > 14V but < 15.

 

[TwoManyXS1Bs]

I'm suspecting a weak battery.
The 80-83 models alternator has one rotor brush powered by 12v, the other brush is grounded by the regulator. Reverse of the 70-79 models. Knowing that, have a look into the charging diagnostic thread:

http://www.xs650.com/threads/expanded-charging-system-guide-in-progress.10561/

 

[gggGary]

Report back on what you find? We love to hear how these things are resolved!

 

[5twins]

The brushes are considered a wear item on these bikes. Once they wear too short, charging output drops off or stops completely. They're one of the first checks you do if charging issues crop up because it's pretty easy and relatively cheap to fix. It could also be as simple as the slip rings the brushes bear against being too dirty and in need of a cleaning.

 

[zybercom]

Thanks guys for your responses. Here's what I found so far:
I did not seem to get a response from the "slap test"
The battery connections are clean.
I did find a green wire had a spot that was rubbed through and touching metal, I covered that with electrical tape.

The voltage at the battery is just over 13 volts even when revving.
While checking the battery voltage I noticed the fuse cover was very hot, it is the 20A main fuse.

Also while running the engine my headlight does brighten a little when I rev it.
But I also noticed the tach and neutral lights flickered somewhat when the signal flashed.
Lastly there seems to be a little corrosion on the components in the one picture--is that the brush connector?

Thanks, I'm a little baffled...

 

[Superjet]

Go thru curly's guide 1 step at a time. You will get thru it and find the problem....I recently went thru it myself....twice!!

 

[zybercom]

Yes I've been trying to go through Curly's guide. I don't always know what components are called or where to look for them, but I am trying!

 

[TwoManyXS1Bs]

...I did not seem to get a response from the "slap test"

While checking the battery voltage I noticed the fuse cover was very hot, it is the 20A main fuse...

Sounds like you're chasing more than one problem.

The fuse should NOT get hot. First, it means a poor connection, resistance, producing heat. It also means that something is pulling a lot of current, possibly a damaged rotor.

Slap test fail could indicate a failed rotor. Do the rotor tests...

 

[gggGary]

The guide should thought of as a maintenance guide also, each of the basic areas you check should be used as an opportunity to clean, make certain of good continuity. The fuse clips often get weak and eventually fall apart, if that's the issue, replace the fuse box. Remove the battery ground strap, check for rotted wire, loose ends, clean up bolt, frame at attachment. Remove and check brush lengths. Yes check the rotor for 5.5 ohms. The ignition switch allows water into the contacts, remove and clean the insides. There's lots of "could be's"

Lastly there seems to be a little corrosion on the components in the one picture--is that the brush connector?

Yes those are the brushes, pay attention to the "unusual" way they are installed while removing. This is typical needed work on any 40 year old motorcycle.

 

[zybercom]

Did a little research (youtube) and learned a little about how some of Curly's tests look. For me, It helps to be able to watch someone do it rather than just relying on my own interpretation of the text. I did the resistance test on the rectifier (3 white wires vs the brown) and apparently thats ok all 3 readings were consistant. I also re-ran the slap test with the cover off and definitely got "slap" !
I took out, and checked both brushes, they're worn but have a ways to go yet to the indicator line/mark.
Getting back to the fuse box, gggGary, you are right about the fuse clips. One disintegrated while I was handling it. Is a new box something that you'd recommend Mike's for or some other vendor? Anyway, the main fuse still gets hot when he bike is running, but I also discovered the one that say "head" is also getting hot. And, the Main fuse has 12 volts across it all the time, but doesn't get hot with the bike turned off. I'm guessing there may be a short involving the headlight and the signals, but its just a guess at this point. Any thoughts on any of this is truly appreciated. I opened the headlight bucket for a look-see, man, what a menagerie that is!
I want to say thank you for the guidance and the encouragement I've received on this site. You are some good guys!

 

[zybercom]

The brushes are considered a wear item on these bikes. Once they wear too short, charging output drops off or stops completely. They're one of the first checks you do if charging issues crop up because it's pretty easy and relatively cheap to fix. It could also be as simple as the slip rings the brushes bear against being too dirty and in need of a cleaning.

I ordered a new set of brushes. Thanks 5twins.

 

[gggGary]

Go back in the headlight shell, pay close attention to the grommets at the back of the shell, pretty common for them to crack and let the sharp shell edges saw through wire insulation.

 

[nj1639]

Don't be intimidated by the connectors in the head light. They're all one off and can't be swapped.
The pigtails are another question. All blacks are grounds. Sometimes the flashers dark brown and dark green wires can get dirty and look black.

Nice bike!

 

[TwoManyXS1Bs]

... Is a new box something that you'd recommend ...?

Do a forum searches on: "fuse block", "fuse panel", "fuse box". Click "titles only" for each. Numerous recommendations, and install tips...

 

[zybercom]

Go back in the headlight shell, pay close attention to the grommets at the back of the shell, pretty common for them to crack and let the sharp shell edges saw through wire insulation.

I looked at those grommets gggGary, they still look intact, no rub through that I could see. Thanks for the suggestion.

Do a forum searches on: "fuse block", "fuse panel", "fuse box". Click "titles only" for each. Numerous recommendations, and install tips...

Will do. Thanks.

 

[zybercom]

Don't be intimidated by the connectors in the head light. They're all one off and can't be swapped.
The pigtails are another question. All blacks are grounds. Sometimes the flashers dark brown and dark green wires can get dirty and look black.

Nice bike!

It does look intimidating in there! Thanks!

 

[zybercom]

While I had the brushes out to replace them I did an ohm test between the slip rings and got 0.00. Is my rotor trash?

 

[Jim]

While I had the brushes out to replace them I did an ohm test between the slip rings and got 0.00. Is my rotor trash?

0 ohms is a dead short. That's bad. Should be about 5 ohms.....

 

[gggGary]

is your meter on the correct range?