Does size matter .. How big is yours? (Spark, that is)

[Taid]

I, until recently, have had no problem starting the bike, there are other problems with running, but they are other topics.

I have not really ridden it since buying last October .. just around immediately local streets .. but it has been sitting idle for the last month or 6 weeks.

Anyway, decided it was time to give it another airing about a week ago, but it didn't think that was a good idea and it just would not start.

First thing, check for spark .. (not the easiest thing to do on one's own) .. nothing.

I went into the magneto and cleaned and checked it out .. all appeared ok, so reassembled the end cover and tried again .. hallelujah a spark, but so tiny as to be almost not there and I doubted that it would be enough to fire it up ..

But I was wrong, the bike started third kick .

I know I won't get as good a spark out of a magneto under start conditions as when it is running, but how big a spark should I expect to see?

As a rider to this topic, is there anywhere, or anyone, in the Telford area who can check and set up the ignition and carburration .. the re-learning curve is rather steeper than I expected.

[SPRIDDLER]

I went into the magneto and cleaned and checked it out .. all appeared ok, …….

Just to clarify, when you 'cleaned' it did that include the c/b points and slip ring?
With now't better to do I started recommissioning my scruffy '54 G3LS yesterday which I haven't run for three years and no spark. I only got a weak spark after cleaning the c/b points and slip ring but very weak. A very good mag should spark a gap of up to 1/4" at kickstart speed and be 'fat' and blue in colour rather than reddish and thin. My mag hasn't needed refurbing in the 20 years that I've had the bike and I suspect at the very least the condenser is ageing and it's time to send it away for a complete o'haul.


It'll be difficult getting help setting your bike up during the lockdown. It's not difficult to do it yourself and there's help on here. Do you have the Owners and Workshop manuals? If not, see here under 'Books'
http://archives.jampot.dk/
There's an excellent carb set-up guide on various websites (Burlen, Amal, Hitchcock's).

EDIT
You might check that the Pilot jet is clear. They can become gummed up with today's ethanol petrol. When starting and up to about 1/3rd throttle it's mostly that jet which feeds fuel to the engine.

[Taid]

Thank you, S.

Not sure how correct the magneto is, in that it has a metal end cover which, I read somewhere, was typical of versions used on stationary engines.

Cleaned the points and the HT contact on the coil and and the cover .. but 'slip ring'? thought that was alternator stuff.

Checked the points opening and closing but, having still to get some new feelers, didn't check the gap.

Nor, for the same reason, did I check the plug gap.


Certainly the spark I have doesn't look big and fat, but at least, the bike is back to starting easily, whatever the spark.

Had a tweak at the carb and it nows runs better, I can even fully open the choke, which I have never been able to do until now.

But I have found I have another problem .. No output from the Dynamo .. I have a put DVR-2 on to run at 12v with negative earth .. have flashed the field coil, but zero output from the dynamo .. cant be 100% sure it was working before .. it certainly wasn't when I bought the bike, but closing and breaking the contact in the original 6v controller did get it working, .. probably best to replace or refurbish it .. no desperate rush ..

Just been reading the workshop manual about testing it .. will give that a try but doubtful as it shows 0 volts when running all connected ..

[56G80S]

I think there's a bit of confusion. I checked your profile and it's 56 - but maybe 57 - machine. So it'll be an SR1 mag as you're clear it's not an alternator. In my view they are really good kit! The metal end cover may've been added for all we know and in any case a stationary engine SR1 ran my 56G80S while the original mag was away for repair. From memory the gap should be 12 thou at the points and 22-25 at the plug (or a sliding fit for your thumbnail).

The old style condensors are notoriously fallible and I've had them fail out of the box and others run for years. Get a BrightSpark Easycap. As for the dynamo it's not that important as with a sound battery to give brake lights I can recall making the 220 odd mile run to London with no dynamo in at all. Charge up overnight and ride back up and with LEDs now probably no need for the charge up! I would recommend Tony Cooper for dynamo and mag repairs. I'd focus on getting the engine working right.

There should be the kind of spark that Spriddler describes and if not there's something wrong that needs fixing before it stops working. There's a whole range of things that can affect the spark and my only advice would be to change things one at a time and be very clear what the working set up was before each change so you can take a step back if things get worse! Points, condensor, spark plug or it's cap (take the cap off and check just using the exposed end of then HT lead), HT lead intermittent fault and the rest.

Johnny B

[Taid]

Thank you 56...

The bike is a bitsa .. frame is March 56 .. Supplied to Ron Lake of Devon .. the engine is a 57 model, built Dec 56 .. Supplied to F Ray and sons, Eastbourne .. the rest - who knows?

'as is' was registered as a 1957 with age related number in 1987.

Certainly can run locally on battery alone, which is I all I plan for a while .. but have extra electronics .. STS flashers and SBS brake light and a remote 'ignition' switch .. charging the battery after use would be OK at the moment, but long term would like to get the whole lot working ..

[SPRIDDLER]

The 'Slip ring' is as you said the brass collector ring in the mag for the HT lead upon which bears the spring-loaded carbon brush.
You seem to be making progress with testing the dynamo but if you aren't aware of it there's an excellent practical website here covering all things leccy:
https://matchlessclueless.com/
As John said, if you have an SR1 mag a first class easy to fit condenser replacement is available from Brightspark Magnetos (a club member) and their website also has excellent techy info.
http://www.brightsparkmagnetos.com/

[willowbedone]

The 'Slip ring' is as you said the brass collector ring in the mag for the HT lead upon which bears the spring-loaded carbon brush.
You seem to be making progress with testing the dynamo but if you aren't aware of it there's an excellent practical website here covering all things leccy:
https://matchlessclueless.com/
As John said, if you have an SR1 mag a first class easy to fit condenser replacement is available from Brightspark Magnetos (a club member) and their website also has excellent techy info.
http://www.brightsparkmagnetos.com/

Hi Neville do they supply a condenser for a sr1 I've looked on the web page and cannot find one The condenser in mine looks like a BMC mini one ( I don't expect a bright spark one to look the same ) If you know the part number would you be kind enough to put it on here please
Ian

[Groily]

Try this: http://www.brightsparkmagnetos.com/easy ... as_SR1.htm
Bit of fettling, but not hard, and the pix take you through it if you want to go that route.

[willowbedone]

Try this: http://www.brightsparkmagnetos.com/easy ... as_SR1.htm
Bit of fettling, but not hard, and the pix take you through it if you want to go that route.

Thank you it looks easy enough Just need to order correct one
Ian

[56G80S]

Just take it slow and follow the instructions and it's all good. I bought two but haven't needed the spare.

Johnny B