Ignition question

[tornitore45]

Yes, yes, yes...... the bottom line a lethal current sends around 100mA through the heart. Depending on the way the source is applied 1.5V from a AAA battery can be deadly and a 20,000V from a spark plug can be just a nasty tickle.
Fast transient do not penetrate the skin too deeply. 60Hz and DC follow the veins and arteries. I remember feeling the heat where the vein in the arm are.
Hand to legs path depend from your shoes soles and the ground material. Dry sand is insulating, salt water is very conductive.
DC grabs you, AC give a chance to let go if is not too strong.
Callous hand have some resistance a baby butt take electricity much better.
Pierced skin make good contact one gen feel it with a 9V battery
Hand to hand has a path through the heart. Right hand to feet is a bit safer than Left Hand to feet but not much to count on it.
Each individual is different.
I worked all my career with medium voltages below 3,000V AC and DC managed to reach retirement without injuries but without being paranoid, just careful and never let anything distract you. Also being mindful of where the danger is and having a well constructed circuit.

 

[Ken I]

I did not take long for this to go way over my head. Seems like some folks have had success with setups others say cannot work. Ignition systems are not my area of expertise.

Gordon - do a search - there are plenty of threads on ignition systems.

The following is by a member who had a problem with in series plugs - for the reasons I outlined earlier would only fire on one cylinder -

damn thing won't run

As Mauro pointed out it can be made to work but I'd rather just go for a duplex coil - in the linked article he got one FOC from a scrapyard.

Regards, Ken

 

[chrsbrbnk]

might try these guys they have a number of different model ignition systems you can buy .

 

[Charles Lamont]

A wasted spark system uses two coils or a duplex coil (one primary and two secondary's) - they both fire together, once per revolution so each plug fires once at the end of the compression stroke and again at the end of the exhaust stroke - this is the "wasted spark".

Using a single coil to fire two plugs in parallel will only end in tears. Similarly using a single coil to fire through both plugs in series means the cylinder block cannot be grounded and has "float" to such high above ground voltages that it will strike to earth via other point or hall effect sensor wiring resulting in a single cylinder only firing - not to mention damage to electronics etc. etc. Don't even think of attempting either of these methods.

The Novus-2 coil I have mentioned is sold specifically for wasted spark systems. It has a single secondary coil with a wire from each end of it going separately to a plug. The hall sensor, one side of the primary, and engine frame all go to common ground.

 

[Rustkolector]

Lot of good discussion here, but like Gordon, over my head also. All I really know is that the 3 single coil waste fire CDI ignition ignition systems that Roy Sholl built for me have worked flawlessly for many, many, many hours on twin's with both 360 degree and 180 degree crankshafts. The video link is a 180 degree crank.
Jeff

 

[tornitore45]

Ken, I read the link you posted damn thing won't run

Initially the author says the cranks are 90 degrees apart but the correct and say the cranks are 180 degree apart.
The picture shows an In-Line 2 cylinder 4 strokes.
A boxer configuration has crank 180 degrees but the cylinders are 180 degree there fore if we rotate one cylinder and its crank 180 degrees we have an In-Line arrangement. In this case the cranks are aligned Zero Degrees.
Such a configuration will work fine with wasted spark but the pistons runs "together" and the engine would be awfully unbalanced.
The original post shows an engine that is somewhat better balanced by having the piston moving in opposite direction.
The cylinder are in line but the crank is 180 so the firing point can not coincide Power Stroke with Exhaust Stroke
The spark events will be as follow:
Cylinder 1 at End of Compression (good) and at the End of Exhaust (wasted but harmless)
Cylinder 2 at End of Expansion (180 degree too late) and at the End of Intake most likely resulting in backfire.

There is perfectly logical explanation why a wasted spark system does NOT WORK in a straight In-Line engine with 180 degrees cranks.

By repeating the analysis on a classic Boxer (180 Cylinders 180 Cranks)
or the equivalent In-line (0 Cylinders 0 Cranks) You can tell the they are basically the same configuration.
One find that the spark events repeat identically in BOTH cylinder at TDC End of Compression and TDC End of Exhaust

I hope the original poster see this so he can realize why his engine did not fire the second cylinder.

 

[awake]

I told him Look and I gave a long French kiss to the wire.

Pictures, or it didn't happen!

 

[Charles Lamont]

[edited]
The picture shows an In-Line 2 cylinder 4 stroke.
In this case the cranks are aligned zero degrees.
Such a configuration will work fine with wasted spark but the pistons runs "together" and the engine would be awfully unbalanced.

The classic four-stroke straight-twin British motorcycle engine* is a 360 - it works better with a single carb than a 180. The even firing and lack of 'rocking couple' can make for a smoother engine than a 180 anyway.

*AIUI that's Triumph, Norton, BSA, AJS, Matchless, Ariel, to name but a few (but - I am not a biker).

 

[tornitore45]

The only thing I can tell you, it was not that exciting and the wire did not participate.

 

[scottyp]

The cylinder are in line but the crank is 180 so the firing point can not coincide Power Stroke with Exhaust Stroke
The spark events will be as follow:
Cylinder 1 at End of Compression (good) and at the End of Exhaust (wasted but harmless)
Cylinder 2 at End of Expansion (180 degree too late) and at the End of Intake most likely resulting in backfire.

There is perfectly logical explanation why a wasted spark system does NOT WORK in a straight In-Line engine with 180 degrees cranks.

If I remember correctly, my old Yamaha 400 special (4 stroke inline twin - and not the smoothest engine on the planet) had 2 single ended coils and my buddies KZ 1000 (4 stoke inline 4) had 2 double ended coils (wasted spark). Makes sense to me.

 

[Steamchick]

Charles L: You forgot Rudge - the fore-runner of most British parallel 360 crank Twins I think? -And of course there were others... But not to waste this Thread. You have named the "post-war majors... Well done - (IF not a motorcyclist. "Biker" oft gets mis-understood by other who enjoy riding 2 wheels - with pedals - and sometimes electric motors - instead of Infernal combustion engines.).
K2 (An occasional Motorcyclist!)