A10 with Distributor Ignition. Help please!

[Fred Gassit]

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!

[Greybeard]

Might be the same as this one: http://goo.gl/jckFjO

[Fred Gassit]

Thanks, we looked at the 18D2 cap, but it seems to be quite different... 

[bonny]

What powers the ignition system ? Has the bike an alternator fitted ?

[Beezageezauk]

Hi Fred, 

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

Beezageezauk.

[Fred Gassit]

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!

[Triton Thrasher]

The only really common twin distributor was the one on the Fiat 126.

Google up some pictures and compare.


Similar?

[chaterlea25]

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

HTH
John

[Triton Thrasher]

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

HTH
John

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

[wilko]

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.

[KiwiGF]

Have you tried swapping the plug leads over?

As per prior posts you have some options to bypass the dizzie for trouble shooting purposes....

[Fred Gassit]

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.   

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?

[duTch]

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

[KiwiGF]

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.

[Triton Thrasher]

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.