Author Topic: A10 - removing the magneto? Refitting and timing?  (Read 2378 times)

Offline twr7cx

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I have a BSA A10 Goldenflash (1961 originally sold in South Africa) that has been in storage in a few pieces for the last thirty years. Currently putting back together. Tried to start it but it wouldn't run, backfired a few times. I imagine the magneto is in need of some attention after all this time and so I intend to open it up and check the brass parts for tarnishing and give it a clean. But I'm unsure of the removal and refitting procedure. I understand that there are three nuts holding the unit in place and a chain driven gear in the right side of the case. Any tips or tricks on removal? And how is the timing set on refitting?

adm edit: removed img tags from large images. Please use only photobucket's readymade clickable thumbnails.

The plate on it has the following information:

K2F 423790
AC 361

Online bsa-bill

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Re: A10 - removing the magneto? Refitting and timing?
« Reply #1 on: 02.02. 2014 15:25 »
Hi  twr7cx

the magneto is gear driven.
you can clean it in situ, most important is the slip ring which you can get to  by removing the top pickup,
cam ring and points want a look at to.
I'd check the timing before removing the magneto

use the search feature here to find posts on both "magneto" and "Timing"
 probably someone will post a fuller explanation (sorry I'm rushing out at the moment)
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online RichardL

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Re: A10 - removing the magneto? Refitting and timing?
« Reply #2 on: 02.02. 2014 15:32 »
If you don't mind, I'll call you "Scott" (Just a name I made up, but seems to suit you).


I went back and looked at your previous posts and it seems no one has mentioned that, if you happen to get this bike started after sitting for 30 years, it is likely to soon need an expensive rebuild due to oil starvation at the rod journals. Ask me how I know. If you rebuild it now, clearing all oilways including the sludge trap(ped) inside the crankshaft, it will still be expensive, but probably less so.

I'm certain that if tune-up tips are still your first interest, better sources than I will soon respond. On the fitment side, yes, three nuts hold the magneto and one of the three is on a rod-like extension to reach where no tool will go. The mag is gear driven. The dynamo is chain driven.

I suggest buying a Haynes manual and getting tips from the members here about what to do differently than written there. Also, you need a parts book for your year model, available from many sources.

Looking forward to hearing about your progress.

Richard L.

I see someone else has posted while I have been typing, so, apologies for any repitition.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at for details.

Offline bikerbob

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Re: A10 - removing the magneto? Refitting and timing?
« Reply #3 on: 02.02. 2014 16:14 »
You have been given some very sound advice in the previous post about trying to start a bike that has stood for a number of years it could turn out to be very expensive.  But if you are determined then at least before trying to start it and I assume you have changed the oil and cleaned the filter in the oil tank and removed the sump plate and cleaned the filter in there. Take the plugs out and using the kickstart turn the engine over and with the oil filler cap removed look to see if oil is returning via the hole in the top of the return pipe it could take awhile but at least you will have the satisfaction of knowing that oil is circulating in the engine. Another tip is when you do get it to run hold your finger over the hole in the return pipe for a few seconds as this will force the oil up that very narrow rocker feed pipe to feed the the rockers and clear out any air.

Offline muskrat

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Re: A10 - removing the magneto? Refitting and timing?
« Reply #4 on: 02.02. 2014 19:23 »
I agree with Richard. I always rebuild a new acquisition except for the last one. The A65 lasted 1000 miles then blew to smithereens, and that was after doing all the usual things that bikerbob has mentioned.
Good luck with it.
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Muskys Plunger A7

Offline Rocket Racer

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Re: A10 - removing the magneto? Refitting and timing?
« Reply #5 on: 04.02. 2014 06:10 »
the mag code 361 meaning "March 1961" so the right one for your bike  *smile*
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Offline a10gf

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Re: A10 - removing the magneto? Refitting and timing?
« Reply #6 on: 15.02. 2014 02:31 »
the removal and refitting procedure
How it's going ? See the engine scan, you see the gear system on the timing side. Remove the timing cover, remove the autoadvance unit, then the 3 nuts.

A10 GF '53 My A10 website
"Success only gets you a ticket to a much more difficult task"

Offline wilko

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Re: A10 - removing the magneto? Refitting and timing?
« Reply #7 on: 15.02. 2014 06:16 »
I think you've all scared him off with dire tales of engine blowups!

Offline bikerboy

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Re: A10 - removing the magneto? Refitting and timing?
« Reply #8 on: 19.02. 2014 02:54 »
I know it sounds basic but are the leads on the right way round  *smile*