650SS Overcharging and Undercharging

My 62 650ss charging system charges at 8 to 8 1/2 v at average driving RPM which is a bit much, and starts to boil the battery after a while.
Then I switch the headlight on and it drops down to about 6 v which eventually flattens the battery.
It's a bastard because I can't ride at night too far! And I am destroying the battery.
What kind of regulator do they have? I can't find that they employ any kind of regulator at all, except a couple of wires going to the headlight switch as some sort of cut out? Which I may not have hooked up right?
Thank you

Sounds like you may have wired it wrong, but most riders are happier after converting to 12V, with a Zener diode or some more modern regulator.

If you do that, you'll still have to wire it right!

TBolt said:

What kind of regulator do they have?

Click to expand...

There isn't any actual 'regulator' as such. In this system, a particular two out of of the three stator wires go to the rectifier, and they should produce sufficient output to keep the battery charged (and power the ignition system, if coil ignition).

The "third" stator output wire normally powers the headlamp directly, via the lighting switch.

it sounds like you may have a coil pair in the stator shorted , or open circuited, not producing full amperage with headlight on.

There are 6 coils in the stator...each pair that are diametrically opposite are wired in series, giving 3 such pairs. one pair is brought out on one of the stator leads ( can't say which until I refer to my manual at the office) and this is for daytime running without lights and produces 1/3 stator output. The other 2 pairs are wired in parallel and are brought out on the other stator lead, giving 2/3 output. The headlight switch selects 1/3, 2/3, or 3/3 output depending on position of switch.

There is no over voltage protection....I put in a switch to open-circuit the stator for daytime running after battery boil over took off chrome on primary case and left muffler. With a magneto, battery is only needed for brake light in daytime, unless you are in a jurisdiction that requires MC's to run lights in daytime. I have changed to 12 volt...only requires changing the lamps and battery....the stator will put put sufficient voltage if all coils are patent. I would use one of the voltage regulators that are now available, rather than a Zener.

If you have a good VOM, test continuity and resistance between both stator leads and common lead (brown one I think). This is not an absolute test, as the parallel wired coils can have a fault that is masked. A rough indication that all is well would be open circuit between all three leads and the MC frame ( no shorts to ground), then resistance between one of the green leads and brown is half (or twice) the other green and brown. The parallel wired pair should have 1/2 the resistance of the single pair. An open circuit would indicate a broken wire in the coils or an open in a lead wire.

A more thorough diagnostic would be to disconnect the three stator leads, then with engine running at say 2000 RPM, measure voltage between each of the green stator leads and the common (brown) lead. The voltages should be the same if all coils are patent. A low voltage value would indicate a new stator. This must be done on AC voltage setting....it is an alternator after all.

Pm me if you need those wire colors coming off the stator.

Manual with wiring diagrams:

http://www.classicbike.biz/Norton/Repai ... 0-1968.pdf

The commonest problems with the 6V alternator sysstem, which can cause undercharging like yours, are:-

stator coils short-circuiting to their iron core, because of vibration and flimsy construction; and

some sort of failure of continuity in the circuit that switches the extra charging coils in, for the headlight. Often a fault in the shoddy headlight switch.

Just as an aside, you can obtain 6v and other values of zener diodes.
Not always in large wattages though - and this was not a factory voltage regulating system. ?

Ok, great info here you people!! I'll be working on her tomorrow and I'll try everything you've said.
I'll keep you posted, thanks to all

Unless your 650ss has been fitted with a more modern day stator and r/r, it will have the Lucas 6volt stator that could be changed to 12 volt when fitted with a Zener_diode connected to a heat sink.
You just changed two wires over to change from 6v to 12v.

http://en.wikipedia.org/wiki/Zener_diode