1981 250 Superdream Charging system problems.

[joef]

Hi all,

Sorry to start a new thread but I haven't found anything specific enough when searching to answer my questions.

I have a 1981 Honda CB250N Superdream and I have a problem somewhere in the electrical system.

I have tested the stator with the ignition off and have 0.4ohms between all three yellow stator output wires.

I have tested with the bike running off a battery and have 11VAC, 13.5VAC and 13.5VAC between the yellows. These rise to 45VAC, 50VAC and 50VAC when the engine speed is increased.

In addition, if I reconnect the REG/REC I get 16VDC output at idle and around 60VDC when revved! I have another used spare REG/REC which I have also tried but which gives very similar results. I was testing between the green and red as I believe the black is a voltage sensing input.

Is my stator at fault here or is it the REG/REC, or both?

Any help or advice would be greatly appreciated,

Thanks, Joe
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- 1981 Honda CB250N Superdream -

[yen_powell]

Back in my youth 250 Superdreams were famous for their regulators breaking and were usually replaced with one from a different motorcycle manufacturer. Nowadays you can probably buy an aftermarket replacement, aren't they called something like MOSFET?
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[WD Forte]

The stator sounds ok, the reading are consistent with a CDI stators asymmetrical windings
but the 16v is too hign and the 60 way too high
is this under load ie connected to a battery?
The RR does sound as if its knackered but a bad earth on the green and bad connections
on the black sense wire will drive output voltage up too
One thing I do on my Honda is permanenetly clamp the black wire ( sense) to the Red/White (battery pos)
and make sure the green has a damn good bond to battery neg and frame
before condemning the RR.
If you still dont have a steady 14V-ish the RR is knackered.
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[joef]

[joef]

Update in case anyone finds this thread after searching.

I have put it all back together now with a new battery and everything is fine. It stays at about 12.5 running at idle and 13 ish when revved so I'm quite happy with that. I may play around with the voltage sense wire as I suspect that's what is playing it up.

The strange readings I was getting were, I assume, because I didn't have the regrec connected to anything, so there was no load across it and no voltage sense to control it.

hth someone else.

Joe
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- 1981 Honda CB250N Superdream -

[stinkwheel]

Yes, the voltage sense is usually connected to a switched live but it's not uncommon to simply hook it up to the red, it'll still work like that.

It regulates its output based on the voltage in that wire so if there is zero volts, it wont regulate at all.

They use the sense wire so it's more responsive to what's actually going on in the loom rather than the battery voltage.

And yes, it was common to use superdream reg/recs to replace less reliable ones in other bikes. Particularly 70's suzukis which had really nasty and unreliable seperate regulators and rectifiers. How to fit a superdream reg/rec to your chop used to be a common article in custom motorbike magazines.
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