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User avatar
By stinkwheel
#95413
Got one of the high output lucas stators on my 350 bullet.

The insulation of the wiring going into it has become brittle an inflexible through exposure to heat and oil. It splits a little at the stress point where it exits the potting compound every time the stator is removed and has now got to the point where the core is exposed. Being potted, I can't go in and replace the affected wires with new ones (I'd have soldered in a new piece of multicore on an OEM stator).

Are there any known repairs for this? If not, I'm thinking of de-greasing it as far a humanly possible then covering that whole area in a man-size blob of thickened epoxy.

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User avatar
By Adrian
#95418
Being potted, I can't go in and replace the affected wires

How long have you been potted, Stinkwheel? :D

Sorry, couldn't resist.

Are you able to pare back the potting compound far enough slip some self-amalgamating tape round each of the wires where the insulation has cracked? How old is this stator?

I came across one of these stators for a good price at Netley Marsh a few years ago, but on closer inspection it had exactly the same problem as yours, is there some better way of supporting or routing the leads to reduce the stress, or protecting them from the chemical degradation caused by the oil (apart from a belt-drive conversion)?

A.
User avatar
By stinkwheel
#95423
Cheers, it hadn't occurred to me to pare away the compound. If nothing else, that'll give me a good recess to apply epoxy into.

The logical thing would be to have a clip of some sort remote to that stress point so a short loop of cable exiting the stator is held rigidly in position. It may then be prone to failure at the clip instead but it at least gives a length of cable to solder into.

Either that or have a static connector recessed onto the potting compound, be that a simple row of spade terminals or some form of multi-connector block. In fact, if it fails again, that's what I'll do. Carve out a recess in the potting compound, solder terminals onto the ends of the wires and bond them in place. Then the cable is a replaceable flying wire.

I suppose the real thing would be to have cable with insulation that doesn't go hard and cracked when immersed in hot oil in the first place... But it is Lucas we're talking about here. Silicone or even a braided steel/kevelar sheath on the first few inches would make sense.
User avatar
By Adrian
#95424
If you can a) pare back the old potting compound far enough, and b) there's enough room under the primary cover when you want to fit that back on, you could permanently epoxy the smaller half of one of these into place.

https://accessories.hitchcocksmotorcycl ... J-1200.jpg

My worry is something like that would then stop you getting the primary cover back on. Our hosts do offer spacer thingies for taking the covers out a bit, though with VAT it's now £72. Still cheaper than a new Lucas 4-wire stator @£112

Failing that, magneto ignition and acetylene lighting!

A.
User avatar
By stinkwheel
#95425
I think a simple row of male spades bonded in place would probably be better than half a multi connector. Then you could connect to them using those 90-degree female "flag" connectors, which would land up a lower profile than the cable itself.
User avatar
By windmill john
#95426
I was going to make a joke, saying ahh let them rub together, you’ll get a single phase alternator then, :roll: possibly only half wave.

Then I thought, no, teach me. What would be the implication if the violets touched, or in fact the implication of any touching?

And the difference if your reg/rec wasn’t solid state?

Actually this is too deep, because I may not understand your answer!
User avatar
By stinkwheel
#95482
I'm actually not sure. It would effectively give you a bigger coil but with two paralell branches. I suspect it would go over-voltage, then it would be a race to see if the reg rec or the wiring fried first. Or the two might be out of phase and cancell one another out. In any case, I doubt it would be conducive to effective function.

Here's my solution to the problem anyway. I used West Systems G-flex epoxy (they glue boats together with it). I applied it in-situ so the wires were bent in the correct direction. I jammed a piece of cardboard between the rotor and stator because the epoxy, while thickened, is still liquid and does flow before setting. The trick is to apply the stuff above where you want it and anticipate how much it will flow down. I don't always get it right but I'm pretty pleased with this.

Image

The excess can be cut off with a stanley knife.
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User avatar
By stinkwheel
#95494
Max normal temperature is 93 C, it goes quite rubbery and flexible at that temperature but re-hardens as it cools.

Oil resistance? As far as I'm aware, you could make a fibreglass petrol tank with it...

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