Author Topic: A10 with Distributor Ignition. Help please!  (Read 1170 times)

Offline Fred Gassit

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A10 with Distributor Ignition. Help please!
« on: 15.04. 2015 09:15 »
Hi all.
My father-in-law has a tidy BSA A10 Super Rocket of 1958 or 59 vintage.
At some point in its life it has been rewired, fitted with an electronic regulator, and most interestingly a distributor ignition system.
After a 2 year lay-up due to ill health we are having no success getting it started, and it looks like there is a fault with the ignition (poor sparks).
I have attached some pictures of the conversion and the components.
Can anybody identify this modification and suggest where we can get spares? particularly a new dizzy cap?

Thanks very much!

Online Greybeard

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Re: A10 with Distributor Ignition. Help please!
« Reply #1 on: 15.04. 2015 09:48 »
Might be the same as this one: http://goo.gl/jckFjO

Offline Fred Gassit

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Re: A10 with Distributor Ignition. Help please!
« Reply #2 on: 15.04. 2015 13:07 »
Thanks, we looked at the 18D2 cap, but it seems to be quite different...  *sad2*

Offline bonny

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Re: A10 with Distributor Ignition. Help please!
« Reply #3 on: 15.04. 2015 15:43 »
What powers the ignition system ? Has the bike an alternator fitted ?

Offline Beezageezauk

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Re: A10 with Distributor Ignition. Help please!
« Reply #4 on: 15.04. 2015 16:04 »
Hi Fred, 

What are the numbers on the distributor body?  They might give us a clue as to the correct distributor cap.

Beezageezauk.

Offline Fred Gassit

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Re: A10 with Distributor Ignition. Help please!
« Reply #5 on: 15.04. 2015 17:47 »
As far as I am aware the bike still has the original Lucas 6V dynamo.
There are no obvious markings on the distributor body or on the dizzy cap.
The way the points are secured with really small allen screws makes me think it might be a one-off custom job!

Online Triton Thrasher

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Re: A10 with Distributor Ignition. Help please!
« Reply #6 on: 15.04. 2015 18:13 »
The only really common twin distributor was the one on the Fiat 126.

Google up some pictures and compare.


Similar?


Offline chaterlea25

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Re: A10 with Distributor Ignition. Help please!
« Reply #7 on: 15.04. 2015 20:22 »
Hi,
The points contacts look oxidised? have you cleaned them?
Looking at what you posted, poses a few questions?
Why two sets of points and a distributer cap ????
With two individual sets of points theres no need for a distributer? has it got two coils wired up?

I would use just one set of points and a twin output coil, and forget about all the palaver with distributer caps *bright idea*

HTH
John
1961 Super Rocket
1963 RGS (ongoing)

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Re: A10 with Distributor Ignition. Help please!
« Reply #8 on: 15.04. 2015 21:19 »


I would use just one set of points and a twin output coil, and forget about all the palaver with distributer caps *bright idea*

HTH
John

Does the cam have two lobes? I can't see. Your idea would need two lobes on a half engine speed cam.

Offline wilko

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Re: A10 with Distributor Ignition. Help please!
« Reply #9 on: 16.04. 2015 01:38 »
With twin points and lobes, there is no need for a rotor and cap? It just needs a plain cover and twin coils. Most unusual setup? And yet there is provision on the shaft for a rotor??? Mish mash of parts.

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Re: A10 with Distributor Ignition. Help please!
« Reply #10 on: 16.04. 2015 08:18 »

Have you tried swapping the plug leads over?

As per prior posts you have some options to bypass the dizzie for trouble shooting purposes....
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1956 A10 Golden Flash (1st finished project)

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Offline Fred Gassit

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Re: A10 with Distributor Ignition. Help please!
« Reply #11 on: 16.04. 2015 10:33 »
The only really common twin distributor was the one on the Fiat 126.

Cor blimey guvnor, I think we might have a winner! Well spotted that man.   *wink2*

The points drive cam has a single elongated lobe, so when it starts to open one set of breakers the other set is still held open.
At that point the rotor arm is aligned with the correct cylinder.
There is only a single 6V coil fitted, so the distributor points the spark at the correct cylinder.
The points were a bit dirty, but I gave them a careful scrub with fine emery paper and the DMM said they were making good contact.
With the HT lead from the coil held near chassis I was getting big fat sparks, but with the dizzy hooked up and the plugs held against the head I couldn't see much at all. Hence the focus on finding replacement parts for the distributor.
Must admit I was bemused by the complexity of the twin contact breakers *plus* distributor.
I thought the A10 would be a wasted spark system?
Is there any advantage to converting to single fire? Maybe if you fit a hotter cam or something?

Offline duTch

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Re: A10 with Distributor Ignition. Help please!
« Reply #12 on: 16.04. 2015 11:24 »

 Without going back to do forensics, did I miss any mention of condensor(s)...??
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

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Re: A10 with Distributor Ignition. Help please!
« Reply #13 on: 16.04. 2015 11:35 »
Hi Fred, the a10 magneto points open every revolution of the crank and a slip ring directs the spark to the correct cylinder so there is no spare spark.

The mag goes at half engine speed but the points cam opens the points twice for each mag revolution.

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1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

GL1800 Goldwing, well, the wife likes it

KTM 950 ADV, cos it’s 100% nuts

1952 Armstrong Siddeley Whitley for rainy days (with wife)

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Re: A10 with Distributor Ignition. Help please!
« Reply #14 on: 16.04. 2015 18:08 »
Bike won't start?

Plugs first. Fit new ones.

Tickle the carb more. Then even more.

There will be a condenser somewhere in the LT circuit, between points live feed and earth.

You can tell which HT lead goes to which carb, by the direction of the rotor arm when a set of points is just opening and checking which cylinder has closed valves.