Topic: 1982 Honda CB650 Battery Dieing

[lindylex]

I recently purchased a 1982 Honda CB650.  I got a new battery for it because the previous battery died while I was trying to learn how to ride it.  The new battery has done the same.  It stopped having enough juice to turn the starter over after 15 minutes. 

How can I fix this?

Thanks

[my79650]

Buy a mulitmeter and trickle charge the battery first. Under the left side cover is the charging rotor, set the meter to ohms and check the slip rings. 4 or more means it's good. But if it is lower it can kill the regulator/rectifier.  Check that first as its easy and these don't charge at idle, see if your headlight gets brighter when revved, i will have to check my manual for the regulator testing and post back for you the testing, or someone else whose good at copying can get you a link if you don't have a manual.
There's an upgrade for this,  do a search on here.
PS: i meant the cover on the left side end of the crank shaft. Not the plastic cover .
,

[trueblue]

My79650, I can't talk for your bike, but my 650, with the headlight on, pumps out 13.5v at idle and 14.2v over 2500rpm.  I would call that charging at idle.  These are the 550's we are talking about here 

Lindylex, you will need a multimeter to go any further.  As said before, first thing to check is the rotor, after this many years the varnish that insulates the wiring breaks down and they short out.  They should be at least 5 ohms across the slip rings, any less and they are on their way out.  If they get as low as 3 ohms you run a serious risk of frying the regulator.  I had this happen on mine, it got down to 2 ohms and killed the regulator. 

[my79650]

Trueblue my machine don't put that out, its 12.something at idle. I did replace the rotor and the r/r last year with new and i get the brighter headlight when revving but stays dimmed down at idle. I was just using my experience with my bike for him; as for his charging system who knows whats been done over the years in parts of his harness; but on the bright side mine is performing great and is even able to run a set of 55w yellow fog lamps without any issues on the steady driving i don't use them when i'm city driving as too much stop and go traffic.

[trueblue]

Trueblue my machine don't put that out, its 12.something at idle. I did replace the rotor and the r/r last year with new and i get the brighter headlight when revving but stays dimmed down at idle. I was just using my experience with my bike for him; as for his charging system who knows whats been done over the years in parts of his harness; but on the bright side mine is performing great and is even able to run a set of 55w yellow fog lamps without any issues on the steady driving i don't use them when i'm city driving as too much stop and go traffic.

Fair enough, I know mine charges at idle, I had my rotor re-wound about 4 years ago.  The fella who did it said it should work a bit better now, when I picked it up.  He reckoned it would be better than new, I took that with a grain of salt.  Maybe there was something to it.   

[my79650]

Whoever did the rewind for you definitely knows his stuff. By him using the newer modern rotor guts and the condition of your entire system i say its great that you charge at idle.