Poor starting on new Amal and BTH Magneto

[davidd]

If your ignition system is producing a spark in the air that seems weak, it is weak. It's not because your particular type of ignition system is producing an "ultraviolet" spark, it's because it isn't depositing as much energy into the ionized channel as some other type of ignition system. The color of the spark is determined by the chemical species present. In the case of a simple test across a spark plug in your garage, those chemicals are almost entirely oxygen and nitrogen (the 'click' you hear is the shock wave). They're the same independent of the ignition source. However, while the color is the same, the brightness is proportional to the total energy produced by your spark system. Brighter is better. No, let me modify that. Brighter is a lot better.

Magnetoman,

Thank you for giving such a detailed and informative answer. It was exactly what I was looking for. If I understand correctly, the color does not correlate with energy, but brightness does. The reason I raised the issue initially was that I had seen various promotions for high performance ignition systems that rely exclusively on the ability to produce the brightest spark. I wondered if this was a gimmick. There are several videos here for example, but the first one demonstrates the vendor's point:

http://www.aquapulser.com/performance_ignition/index.html

Prior to reading your answer I assumed that brightness was not important; that if the spark of any brightness existed it proved that the ignition system was functioning, but you could not draw a conclusion from the relative weakness or brightness of the spark. This is apparently false, but I am trying to understand how an ignition system that produces such an obviously weak spark can aid in producing so much power on a dyno, in competition and many records at Bonneville and other venues. I am not asking for a critique or endorsement of any product, but a critique or endorsement of the field test of producing a spark in the air.

David

 

[Monkeypants]

Many electronic ignition systems require a very low power draw. From what I've read and heard, this is due to the efficiency of the EI vs older systems.
Sort of like the big reduction in power requirement when switching from a 100 candle power incandescent to a 100 candle power LED light.
And yet when designing a really hot ignition system for this twin plug motor of mine, Pazon ended up with a high draw system that uses about the sam e wattage as my old dual point dual coil converted Norton setup that is on the Oz Rapide.
This converted Norton dual points setup is the one that makes huge fat cracking blue sparks when the engine is turned ever so slowly with a wrench. It also starts the bike in half a kick.

I like the idea of set it and forget it timing and no points to play with, but is the E I really as efficient as we are led to believe?

Glen

 

[riptragle1953]

I can't help finding much of this absurd in the extreme. I'd build a twin or single , slap a good Lucas mag on it and it take five minutes to set the points ... maybe 15 more to time it..... and it would run like a charm for years. What else in the world do you want?

 

[Magnetoman]

Prior to reading your answer I assumed that brightness was not important;

What I should have said about brightness somewhere in my post is "all other things being equal." As has been done by companies in the past, it's possible to have high inductance leads that store considerable energy and then trickle it out, resulting in a long, bright lingering arc (lingering in the sense of milliseconds -- still too fast to discern with the eye as anything but instantaneous). However, all the action in the combustion chamber already has taken place by the time that bright, lingering arc extinguishes. That is, it's very bright, but it comes too late to do any good at all for the ignition. What ignites the fuel is that shock wave, that propogates out from the path of the arc at very high velocity. Additional energy pumped into the wake of the arc does little (if anything) to help. So, when I say that brighter is better, I'm comparing two magnetos, or two CDI systems that are properly designed, not a system specifically designed to make a bright flash.

 

[riptragle1953]

Again, these are old machines..... what is the point of all this if your old machine runs fine? One adds extra complication for no good reason..... and then comes the problems......

 

[Big Sid]

All so interesting and easily confusing . I've read that today's super fast drag racers , cars , use very large coils t hat produce a huge ign spark with long duration tails , the jump is sustained over a longer moment . And this boosts longer combustion , more power . I'd long heard that a coil points system had a longer duration tail than a CDI system which was more like a flash bulb going off , less heat and time to set off the chamber burn . Will Magneto man comment on this ? Sid .

 

[Mark Fisher]

Rip, if you don't like it, don't read it, then you won't have to comment on it! Anyway i thought you wanted to be deleted.....

 

[riptragle1953]

Sid
Wouldn't a dragster engine built for no compromise balls to the wall performance supercharged, with a huge compression ratio, need a super powerful coil/spark to run? But why a road going Vincent?
Certainly a twin starts easier with battery & coil as the mag is designed for a 180 degree engine and something lost that improving makes a twin run better. But wasn't this post was about a single? I 'm just waking up again so I'm fuzzy
headed and I see I did not word my post before this one very well at all as I didn't completely say what I wanted to say.
I have never been interested in American style racing engines due to the fact that so many compromises are made for speed the engine needs replacing or rebuilding after every race. My god what a waist me thinks : all this for a 1/10 of a second over another
guy who has spent as much money as you have only to replace the parts and do a lot of work after the race.... let alone running around with three semi's to do it with. Having ventured inside trailer trucks with complete machine shops at the track: I surly was impressed.
A 24 hour road race, to me, is what really shows off the design of a machine.

 

[Magnetoman]

I've read that today's super fast drag racers , cars , use very large coils t hat produce a huge ign spark with long duration tails ,... comment on this ?

In the 1890s the con man E.J. Pennington introduced a motorcycle with his name, with advertisements showing it jumping a narrow river thanks to the extraordinary power given to it by its "long, mingling spark." Pennington went on to try to corner the industry through controlling patents in the UK before his schemes all fell apart. The reason I mention this is, it shows that false claims about ignition systems have been with us since the very dawn of (motorcycle) time.

Reading something about sparks means a manufacturer made some claim, which likely was then put into an article by a non-technically-trained magazine writer. It's not worth commenting on such things without actual information on what the claims are. And, even then, it's very likely not worth the time to understand technically what is being claimed since, based on the fact so many claims about electrical systems have proven false from c1890 to present, odds are there isn't much if any substance behind whatever it was you read.

 

[riptragle1953]

bsaowner,

What is it I don't like? My intent is expressing my thoughts on spark-making overkill on a Vin.
And yes one day I was in pain, mad at the world and did something stupid.
But why do you care?
Can a Comet run sweetly with a compact Lucas mag or not?