Author Topic: Magneto body chamfer  (Read 1416 times)

Offline terryg

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Magneto body chamfer
« on: 01.12. 2013 20:44 »
Hello All - while reassembling a 1959 Super Rocket engine today I tried fitting a refurbished magneto that I bought as a spare.  The magneto I took off the engine has no chamfer on the body, unlike two other s/a A10s I know well.  The replacement also has no chamfer BUT it does not fit.

Anyone else had this issue?  What was your solution, apart from an exchange magneto?

Can I safely take a file to the ally body that won't fit?  It looks like about 0.040" off the offending corner would do it.

Any relevant advice appreciated.

Regards
Terry
'57 'SR', '59 SR, '63 RGS

Offline duTch

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Re: Magneto body chamfer
« Reply #1 on: 02.12. 2013 11:13 »

 Geez Terry, maybe I'm on the wrong medication, I'm trying to get my head around what yer talkin' about but just can't do it....maybe a picture will help, and also the details on the ID plate will help....??

 Cheers duTch
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Online trevinoz

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Re: Magneto body chamfer
« Reply #2 on: 02.12. 2013 19:50 »
Strange that it doesn't fit. Over the years I have fitted standard bodied magnetos to A10s, in fact I have a compy magy on one engine.
Go ahead with the file, it won't hurt the working of the magneto.

Trev.

Offline terryg

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Re: Magneto body chamfer
« Reply #3 on: 03.12. 2013 08:21 »
Hello Trev - the interference between this particular mag body and the crankcases just behind the cylinders is small and I'm guessing that Joe Lucas may not have had exceptional control over the body castings.  I can only assume that this is why two of the mags I have appear to have been 'fettled' with the addition of the flat (or chamfer) on the body.
The previously fitted non-chamfered body has about as much clearance when fitted as the other has inteference.  Both ends of the casting tolerance band?
The spare mag that I want to fit purports to be a K2FC (red label and screw on pickups).  On the one hand it seems a shame to be filing bits off but it does look like the obvious way forward.
My original post was really looking for some confidence before I 'do the deed'!
Terry
'57 'SR', '59 SR, '63 RGS

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Re: Magneto body chamfer
« Reply #4 on: 03.12. 2013 20:23 »
Terry,
             The compy magneto body is different to the standard one.
Think hard before you fit it as you will find it difficult to remove the pick-ups once it is in place. (I know well!)

Trev.

Offline terryg

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Re: Magneto body chamfer
« Reply #5 on: 14.12. 2013 15:15 »
Well, it's on now and Trev - I see what you mean about removing the pickups, even though the engine is still on the bench.  Perhaps a search through the tool catalogue will make life easier.

I've put just enough of a chamfer on the body to clear the crankcases at the rear of the cylinders.  I also had to relieve two of the three steel bushed mounting holes before all three studs would slide in.  Whether the steel bushing is someone's aftermarket mod I don't know, I assume so.

There's an older post on here showing a milled chamfer (Chaterlea, I think), which does look tidier than my hand crafted effort.

Sorry about the lack of photos Dutch - maybe some soon.

Coincidentally I've just seen an ad for a replica RGS with a comp magneto.
Terry
'57 'SR', '59 SR, '63 RGS

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Re: Magneto body chamfer
« Reply #6 on: 14.12. 2013 18:16 »
HI All,
Yes, it was me machining away the mag body but that was to fit a BTH manual advance mag !
Removing the pickup near the crankcase will be difficult/impossible without removing the mag  *sad2*
Still I have had no bother with the BTH since I fitted it and feel the effort was worthwhile  *smile*
As I have said before "show me an areo engine fitted with a Lucas mag?"

Cheers
John
1961 Super Rocket
1963 RGS (ongoing)

Offline Briz

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Re: Magneto body chamfer
« Reply #7 on: 14.12. 2013 23:25 »
I used to run BTH mags, they were great...except in the wet. Almost impossible to keep water out.

Online KiwiGF

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Re: Magneto body chamfer
« Reply #8 on: 15.12. 2013 04:24 »
Hi briz, I assume the not waterproof problem was with old style BTH mags? Not the new electronic models? (I have one of those and so far it works fine in the wet).
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Offline Flatboy 1950

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Re: Magneto body chamfer
« Reply #9 on: 15.12. 2013 06:17 »
I have a K2F mag # 42248E    AC 1053 & it has the flat milled on it.
Everyone here in S.A. seems to believe that every A10/ A7 has to have the milled mag
and that the flat tells you that this mag was originally fitted to an A10 or A7 ....
Is this not the case ???

Offline a10gf

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Re: Magneto body chamfer
« Reply #10 on: 15.12. 2013 10:38 »
Out of curiosity, could anyone post pictures of chamfered vs non-chamfered mag ?
Thanks

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Re: Magneto body chamfer
« Reply #11 on: 15.12. 2013 13:09 »
Hi All
Kiwi,
Theres no relationship between the old BTH and the new B.T.H
The new one is actulally a self generating CDI unit very similar to the (pointless) ignition units on small garden equipment / chainsaws etc

I have not had problems with water on my original BTH equipped bikes, provided that the usual precautions are taken
Water can migrate down the advance cable, but this also happens with any other make of mag

Cheers
John
1961 Super Rocket
1963 RGS (ongoing)

Offline Flatboy 1950

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Re: Magneto body chamfer
« Reply #12 on: 15.12. 2013 13:25 »
Here is a pic.

Offline a10gf

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Re: Magneto body chamfer
« Reply #13 on: 15.12. 2013 13:30 »
^^^ Thanks for the pic, interesting, never seen this mag body before.

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Re: Magneto body chamfer
« Reply #14 on: 15.12. 2013 20:08 »
The BSA magys were all chamfered ex factory as far as I can tell.

Trev.