250 Monza not charging

[cooperplace]

Well, at long last the bike is running but the alternator doesn't charge. I would be very grateful for advice re how to approach this problem. The bike has been changed to 12V by a previous owner, and has a Shindengen SH522-12 regulator, which I think is out of a 70's Kawasaki, like a 900. There are two wires only coming from the case to the alternator, both are brown. The insulation is in very poor condition and is flaking off. Lots of bare copper is visible. I've removed the outer black covering over both wires for a distance of about a foot down from the regulator. The insulation is rubbish all the way down, so presumably it will be the same all the way into the motor.

Might this account for the lack of charge? I'm thinking maybe.

if so, how hard is it to get to the alternator to replace the wires running from it, and what special tools are needed?

of course, maybe when I get in there, the alternator itself might be shot.

Any advice will be much appreciated.

[Rick]

I'm sure you'll get a more detailed reply, but you could start by disconnecting the 2 wires going to your regulator and checking for continuity between them- if they're shorted somewhere there won't be any current to be regulated- there's probably a rectifier in there too.
The alternator should be OK- it's just coils of wire and magnets, and unless the coils get hot enough to burn the insulation off, there isn't much to go wrong- the coils may look like bare copper wire, but they're coated with an insulator- it's just not the thick insulation you see on the wires that come from the stator terminal block.
To replace the wiring from the stator will require a special puller for the rotor, and it can be hard to remove even with the puller- if you use a claw style puller there's a good chance of damaging the rotor.
I'm assuming whoever rewired the Monza had it working before the insulation fell apart- without knowing what was done, it's possible that it wasn't charging, and the previous owner gave up and sold it.
Rick

[DewCatTea-Bob]

[quote= cooperplace ...
" the alternator doesn't charge. I would be very grateful for advice re how to approach this problem. "

____ Not to be too concerned, as I'm fairly sure I know what's-what concerning everything involved with this issue !



" The bike has been changed to 12V by a previous owner, and has a Shindengen SH522-12 regulator, which I think is out of a 70's Kawasaki, "

____ Such common type Jap.regulator-units include bridge-rectifier circuits which won't work properly with the n-c.type alt.stators (which have grounded power-coil circuits) !
So it's most-likely that the Jap.regulator "doesn't charge", rather than it being the alternator's fault.



" There are two wires only coming from the case to the alternator, both are brown. "

____ They may appear to be "brown" now,, but originally (before aging), they were rather more obviously yellow-colored !



" The insulation is in very poor condition and is flaking off. "

____ It's very common (and probably INEVITABLE) for the original alt.stator wire-leads to develop such disintegration-integrity of their insulation-covering !
However the remaining insulation material will still keep the bare-wire separated-apart and functional, (PROVIDING that it's not over-handled [as you've been doing] !).



" Lots of bare copper is visible. I've removed the outer black covering over both wires for a distance of about a foot down from the regulator. "

____ THEN that foot of length is now no-longer able to be trusted and must be eliminated !
You need to curtail your 'handling' of that cabled-wiring, or-else you'll have-to replace it all before it really become necessary !



" The insulation is rubbish all the way down, "

____ Indeed it's no-doubt become ALMOST-worthless for it's originally intended functionality,, however, it's remaining 'mater' will still remain in-place and continue to keep the bare-wire 'spaced' apart (from whatever the bare-wire should-not come into contact with), so long as it's not given any chance to fall out of place (by any unnecessary location-displacement).



" so presumably it will be the same all the way into the motor. "

____ Not necessarily, as a motor that has been left kept together has proven to provide additional protection from the catalystic-elements which accelerate the notorious disintegration. _ So if your motor wasn't apart and exposed to weathering, then it's somewhat possible that the internally-located insulation-material is in better condition. _ But even if not,, so long as it's left undisturbed, the insulation-material's 'bulk' will still hold the bare-wire from making any unintended electrical-contact, and-thus continue to perform it's main-function adequately enough. - (Just don't screw-around with it [before it absolutely becomes completely necessary]!)



" Might this account for the lack of charge? "

____ Of-course it MIGHT, especially if the charging-issue began after you started 'handling' the alt.stator-cable.
But otherwise I'm pretty-sure that your charging-issue originated because of someone who didn't realize that ya can't simply connect-up a common bridge-type rectifier to alt.stator-coils that are grounded (like the n-c.Monza employs) !



" how hard is it to get to the alternator to replace the wires running from it, and what special tools are needed? "

____ That's all something which you really don't want to hear the answer to right-now, and quite-likely don't need to learn about yet, before you address the far more likely culprit that's preventing your Monza's alternator from charging it's battery.



" maybe when I get in there, the alternator itself might be shot. "

____ I much doubt that,, however if you get to the alt.stator-cable and disturb it much, then you'll HAVE-to go-ahead & replace the twin wire-lead cabling (and perhaps also perform some stator-wiring modifications).



" Any advice will be much appreciated. "

____ I suggest that you go buy a (cheaply priced) bridge-block* (at your local electronics-shop) ASAP, so you can then test your charging-system's ability to function (without that Jap.regulator-unit) !
(* All you really need one for, is it's contained pair of power-diodes which should be rated for [at-least] 4-amps & 100-volts.)
__ After you acquire such a rectifier-unit, I'll then be glad to inform you of exactly how it's (very-simply) connected-up !

[JimF]

I had the same thing, that is the insulation on the wires was brittle and crumbling with many exposed areas of copper showing.

I kept thinking if I stripped the wire back another inch I would find healthy insulation since the outer sheath would have protected the wire's insulation from the sun's UV rays, but nowhere was the wire in good shape.

So to put a new pigtail of wire from the stator (think stationary plate holding bobbins or wire) you drain the oil and take the left side engine cover off. Then you have to have a flywheel puller tool, something like eBay item number: 380988190940. This allows you to pull the rotor off the shaft revealing the stator behind it.

I think that I pulled the stator off to change the wires. I used a AC line cord from a mini-tower computer. The colors are wrong, but the gauge is good and the sheath is about the correct diameter.

If you need some help when that time comes ping me.

[cooperplace]

I'm sure you'll get a more detailed reply, but you could start by disconnecting the 2 wires going to your regulator and checking for continuity between them- if they're shorted somewhere there won't be any current to be regulated- there's probably a rectifier in there too.

Rick

Hi Rick, thanks, there is virtually zero resistance between the two wires coming from the alternator. I am making sure the bare sections I can see aren't touching.

[cooperplace]

many thanks everyone for the great advice. Given that it would be nice to keep it at 12V, what regulator should I fit, once I work out what's wrong with the alternator itself?

[DewCatTea-Bob]

[quote= cooperplace ...
" there is virtually zero resistance between the two wires coming from the alternator. "

____ That's already to be expected, as the resistance-level of the coil-windings themselves is already pretty-close to being same as that of a true short-circuit.
__ To be sure that your alt.stator-cable's contained twin wire-leads are actually shorted-together, you need to check for continuity between them with an ohm-meter which has a scale of no greater than 10-ohms, so you can then accurately read ohm-levels under 1-ohm.
And if you find such an EXTRA very-low resistance-level, then only then can you be reasonably-sure that those wire-leads are leaking their conducted power-juice directly to each-other !
__ Please let us know the exact amount of resistance you measure between that pair of wire-leads.

Dukaddy-DUKEs,
-Bob

[cooperplace]

Hi Bob,

Thank you for your very detailed post. The best scale on my meter is 0-200 ohms. It shows 1.6 ohms on shorting the leads, and also 1.6 between the two alternator leads. But with the scale on the meter, those numbers aren't very accurate.

maybe I should tape up the wires and put it all back together with an appropriate rectifier/regulator, and see how it works?

[DewCatTea-Bob]

[quote= cooperplace ...
" Given that it would be nice to keep it at 12V, what regulator should I fit, "

____ Unless you intend to steadily ride over two-hours constantly at RPMs averaged over 5-grand with lights left turned-off and employ a relatively tiny battery, then otherwise your n-c.Monza doesn't have any worthwhile use for any kind of regulator-unit !
Cuz if you keep your chosen load-system's power-draw reasonably high enough, then there won't be any excess power-production that requires regulation.
__ The only reason Ducati employed a regulator, is for when the lights were turned-off,, cuz then the power & load systems would become unbalanced (and-thus regulation would then be of some worthwhile use).



" once I work out what's wrong with the alternator itself? "

____ There's most-likely nothing wrong with your alternator, and I'd even bet that it's stator-cable doesn't (yet) have any short-circuit within, (at-least within the motor-casing).
__ It's certainly more than likely that your employed Jap.regulator-unit (with it's built-in bridge-rectifier) is unsuitable for use with the Monza's GROUNDED alt.stator !!
(If Hans/'ducwiz' were here, I'm sure (in this-case TOO) he'd confirm his-own wording - "a bridge rectifier cannot be used with the corresponding coil, because it does not float." ! - Just as posted in another current thread .)



The best scale on my meter is 0-200 ohms.
But with the scale on the meter, those numbers aren't very accurate."

____ You're right, that's not sensitive enough to give trustworthy readings at the levels under 10-ohms.



" It shows 1.6 ohms on shorting the leads, "

____ What "leads", you mean the meter's-own ?
If so, then either the meter needs a fresh battery, or it needs to have it's ohm-setting calibration adjusted.



" and also 1.6 between the two alternator leads. "

____ I believe that's about the correct resistance-value expected for the n-c.6-pole stator-windings.



" maybe I should tape up the wires "

____ Trying to completely 'tape' that old-wiring can be quite difficult to thoroughly accomplish, and a near-certain slippery-slope once ya get started with the attempt. _ So rather, I'd suggest wire-tubing be slid-over & down onto the exposed bare-wire & it's crumbling insulation.



" and put it all back together with an appropriate rectifier/regulator, "

____ If you expect to ride with lights most always kept turned-on, then there'd be no-use for any regulator ! _ So then all you'd really need is a pair of power-diodes, which can be rather handily employed with the simple mounting of a 'bridge-block' (as I've previously mentioned of) !
__ And even if you'd expect to ride without lights on, it's pretty-easy to add a simple switch-circuit to switch-off one of the diode-circuits so as to cut-down charging-power about 66% (and-thus re-balance the running system [and continue going without any regulator] ).



" and see how it works? "

____ Right, after you connect-up a bridge-block (with it's contained power-diodes), you'll then be able to confirm that there's nothing-else wrong with your charging-system (other than that inappropriate Jap.regulator-unit that you've had connected-up).


Duke-Cheers,
DCT-Bob

[cooperplace]

Hi Bob,

thanks that sounds great. If you have any thoughts on how to wire up the bridge-block, I'd be very grateful,
cheers
Peter