strange goop in magneto - what is it?

[mikeb]

hello
i've pulled out the almost new pickups on my k2f to find strange almost crystalline stuff attached to one of the pickups. so i dragged a rag through the gap under the slip-ring and collected the goop that shows in the photo below. in that photo the lines are of a notepad so you get an idea of the scale.
some of this stuff looks more fibrous so I'm guessing it may be the slip ring degrading or something. the bike has been off the road for a year and the had less than 50 miles on it since back on the road last week after full engine rebuild. ie the maggie has been sitting in a box in the garage, and did very little service for some years before that. the pickups are new Taiwanese hexagonal ones - they work ok. i had cleaned the slipring with a degreaser when the maggie was out, prior to reassembly.
So... what is that stuff? how worried should i be?

thanks

Mike

[mikeb]

ok so further investigations. i think the problem is the new pickups have brushes with very square profiles and they've been scouring out the edges of the slip ring and shaving off slivers of the slipring material, and those shavings are in the previous photo (the goop). see the photo below - there's the 'new pickup' brushes (very square), some 'new brushes' (of unknown manufacturer from an NZ supplier) and 'new lucas' (being new from a UK supplier and claimed to be from lucas). note the 'new pickup' ones are a very different end profile. the black marks next to each brush is a line drawn with it, showing similar hardness. and the slipring in the maggie is white coloured (i'm told some are black)

so i've changed to the 'new lucas' brushes with some new left and right style lucas pickups (not the taiwanese hex sort) and I'll see how that goes.
along the way the new taiwaense brushes also had the brush spring coiled in the opposing direction (to that of the other brushes) and the acorn nut has a different thread ... gotta love these new parts supplies for giving us problems to solve

does my therory sound plausible? other ideas?

[duTch]

 Dunno- I'm still reeling from looking at head stuff

 The maggie experts should be able to set you straighter than I can

[bsa-bill]

I don't see that resembling anything that could have been scraped or come off a slip ring to be honest.
I'd guess it's the remains of some rag or something that's been used to clean the slip ring and has been sitting down there minding it's own business for some time, or the remains of moth spider whatever

[mikeb]

Bill - without getting too forensic it feels fairly plasticy, not organic and it doesn't crumble (like decaying electrified bugs or old rags). your comment suggests slip rings don't degrade like that, so that's encouraging.

at worst I'll see what happens with the new-new brushes/pickups - e.g. if it keeps happening.

keep the ideas coming!

[Greybeard]

Looks to me like the nest of the very rare New Zealand magneto spider. Since there are so few magnetos around these days their numbers have been greatly reduced since the famous magneto spider plague of '56. They are in fact an endangered species. I encourage all of you in New Zealand to leave an old magneto out in the garden so the spiders can use them to lay their eggs in.

In this rare picture you can see one of the shy critters getting ready to rush in quick and lay eggs when the owner removes the pickups!

[muskrat]

Could it be some of the armature wire insulation that's got a bit hot and flung off? Or the paper bearing cups/insulators? i supose if it were either of those the mag wouldn't worl.
Cheers

[bsa-bill]

Shellac??? 

[Scott and Jay]

Hi Mikeb,

A (Dunedin) friend I made on the BSA National Rally in Feb sent his magneto to our local (Wellington) engineer. This is what was found: "The repro pick ups were a mismatch with only one-third contact with the repro slip ring". Since this was also in NZ these pickups might have been from the same supplier as your first set...

[mikeb]

these comments are helpful. i guess it could be shellac but given it still works, and shellac is insulation then its a bit less likely.  its not paper.  i'm going to hope and assume that:
1. this is a weird thing and not a usual sign of maggie failure - that is good news
2. given other comments about mis-fitting NZ pickups it may possibly be ground slivers of slip-ring, strange as that may be. those 'new' brushes did have a sharp edge on that square contact profile.
3. it could also be an endangered species of magneto spider - i had one in the b33 recently and had to hit it very hard with a hammer. annoying

i'll give the bike a run this weekend and check if more of this is appearing with the new-new brushes

cheers

Mike

[bsa-bill]

yet another thought Mike.
has the magneto ever been sprayed with a damproof spray (struggling to remember what it's called) but you know the stuff I mean I'm sure, sort of spray on silicon sealer for plug leads and ignition bits

[BSA_54A10]

Did some in metho.
If it disolves then it is shelac.
Could also be a preserving film that some one forgot to remove before fitting the end cap.

[mikeb]

i don't think any damp proof spray Bill, it didn't do this before the new brushes/pickups in the rebuild.
good tip Trevor I'll try that. i thought shellac was made from bugs of some kind. didn't know they drunk meths

[metalflake11]

yet another thought Mike.
has the magneto ever been sprayed with a damproof spray (struggling to remember what it's called) but you know the stuff I mean I'm sure, sort of spray on silicon sealer for plug leads and ignition bits

My first thought on seeing the picture.

[RichardL]

Mike,

I just skimmed over all the posts here and I didn't see any mention of a visual inspection of the slip ring. If the brushes were scraping the slip ring there should be some obvious signs and they should be centered in the valley, not on the side walls. If you see signs of scraping down the centerline, then I would expect a hump at the leading edge of the brass.

I would really like to hear Beezermacc or Groily chime in on this, as I think more magnetos have passed through their hands than probably anyone else here.

Richard L.