Author Topic: My big Magneto repair project  (Read 14644 times)

Offline LJ.

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Re: My big Magneto repair project
« Reply #30 on: 09.09. 2009 22:05 »
 *lol* *lol* and they *always* get you home! But I bet you enjoyed every minuet of it. Well done nice story.
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline beezalex

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Re: My big Magneto repair project
« Reply #31 on: 15.09. 2009 16:14 »
Glad to hear the issue was minor.  I'm in a similar situation with my back, having had surgery 9 months ago.  Necessity is the mother of invention and a couple of months ago I had the same thing happen.  And yes, with minimal tooling, they can still get you home.  Thanks for the inspiration, I'll be starting my first mag rebuild soon.
Alex

Too many BSA's


Offline a10gf

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Re: My big Magneto repair project
« Reply #32 on: 15.09. 2009 16:34 »
Quote
and a couple of months ago I had the same thing happen
Gives some peace of mind to read I'm not the only one forgetting things, and the back, it's an exhausting pain when it sets in, one had to learn the hard way to start being more careful.

Have had the opportunity to use the bike for a few longer tours in between the continuous period of rainy days, and the mag seems stable and good, and engine running fine. Next, on to some of the other things soon needing attention!

& Thanks, LJ.



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Offline duTch

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Re: My big Magneto repair project
« Reply #33 on: 12.11. 2013 22:54 »
I understand eccentricity(only too well *eek*), but can't understand how a bearing can be eccentric, but can only assume the races are good, but the ID or OD are manufactured out of whack...???..... or do you mean the bearing is round, but is not centred in the casing ?

 Slightly related, just curious- but anyone know what thread pitch is the C/B centre bolt? seems to measure 5/32", but can't pick the tpi? seems about 30 with my not-so-good gauge, closest I can find to that is BSW/BSC both @32tpi -Thought maybe 3BA, but not so fine and doesn't measure big enough?
 Cheers

 Thanks E, just spotted your post in A/B Gasket after I posted- I think I have it now cheers
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Offline a10gf

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Re: My big Magneto repair project
« Reply #34 on: 12.11. 2013 23:04 »
Hi there, the bearing itself is round and fine, it's the bearing's placement in the mag housing that needed a nudge, see this picture > http://www.a7a10.net/forum/index.php?action=dlattach;topic=1375.0;attach=3083;image showing the placement of thinner vs thicker material, to slightly move the bearing (cup) off center vs the housing.

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Offline KenF

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Re: My big Magneto repair project
« Reply #35 on: 13.11. 2013 05:58 »
... but anyone know what thread pitch is the C/B centre bolt? ...

duTch, it should be 3BA (0.161" x 34.8 tpi), and the head should be 4BA (0.248" AF).

Ken.

Offline duTch

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Re: My big Magneto repair project
« Reply #36 on: 13.11. 2013 20:04 »

 Thanks Ken, good to know- didn't think bsc or ww would work.

 a10gf,
Quote
it's the bearing's placement in the mag housing that needed a nudge,
,

 I guess it's what I had in mind, but either misread it or am dyslexic....I may have a similar issue, and the cam ring could be affected similar...?
  I'll continue with this back in 'Cam ring capers'
 cheers
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Offline a10gf

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Re: My big Magneto repair project
« Reply #37 on: 14.11. 2013 08:15 »
^^^
Quote
and the cam ring could be affected similar


To try come up with some more explanation ref. my particular mag: the camring measured fine (no thickness\position difference between upper & lower cam), but still the point gap + timing  varied quite much between L\R. Slightly adjusting the bearing cup (using different isolation material thickness) so the points plate centered properly vs the camring cured that problem.

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Offline pjm01

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Re: My big Magneto repair project
« Reply #38 on: 14.11. 2013 10:49 »
duTch .....  had a similar issue of needing to determine the 'number of TPI' when doing my A7 clutch and I don't have thread gauges. Cut a thin strip of paper and pressed it firmly onto the bolt thread leaving a clear impression of the helix, then by careful measurement and simple counting the TPI's can be found. Also made an impression from the newly supplied nut and compared it directly to the shaft impression ...... they were different, hence nut did not 'pick up on the shaft'. Peter M

Offline duTch

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Re: My big Magneto repair project
« Reply #39 on: 14.11. 2013 12:32 »

 
Quote
the camring measured fine (no thickness\position difference between upper & lower cam), but still the point gap + timing  varied quite much between L\R.

 Yup a10gf same, only have digital 'Clayton-vernier' calipers to measure but couldn't find a discernible difference in cam profile/thickness, except the ring was 2 thou out of round, so gave it a squeeze with the multi-grips but in retrospect, may not've been a good move as the short measurement was across the 'cam lift diameter' (if you know what I mean), so squeezing it to make it equal(longer), also reduced/eliminated the ability to utilise the sloppy fit (in the housing), with packing to completely rectify the problem (just realised that this arvy when playing).
 Have come to a mental block, will add later if able.....

 Pete, thanks- until I bought the (nasty)gauges, I think I used my fingernail, and stopped counting lumps when the measrurey thing got to an inch or fraction of.....
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia