Topic: Aftermarket coil

[c15racer]

I've just got an aftermarket coil. How can I tell or test, which is the correct way to wire it, I need to know which is the live feed in.

I’ve an orange wire and a funny kind of brown colour.

[Bodi]

Just one coil?
Anyway, the actual wiring should not matter. The coil is isolated from ground, so power one and connect the other one to the points. Check the resistance first, I suggest though. With an ohmmeter you should get about the same reading as the stock coil, which is 5 ohms. Some coils for electronic ignitions have very low resistance, like 0.5 ohms - that would blow your fuses quite quickly. There are also fairly low resistance coils that draw much more power than stock, burning out the points and possibly causing battery charging issues. The Dyna 3 ohm coils (green) are as low as I would chance on a SOHC4, and these are too low for the 350 or 400.

[TwoTired]

This might help you.

[SteveD CB500F]

Excellent TT!

Now, not to derail the thread but he said that the gap determines the voltage (?) Surely the voltage is determined by the primary:secondary ratio of the coils. The ability of the spark to jump the gap depends upon the the size of the gap and the properties of the conducting medium (ie the air in this case)

C15: If you have two wires coming from the coil (as well as the HT Lead of course) it shouldn't matter which way round they are connected.

[mystic_1]

Now, not to derail the thread but he said that the gap determines the voltage (?) Surely the voltage is determined by the primary:secondary ratio of the coils. The ability of the spark to jump the gap depends upon the the size of the gap and the properties of the conducting medium (ie the air in this case)

By my understanding, V=IR, so as resistance increases then voltage increases, assuming current remains constant.  So, as the air gap increases, resistance increases, thus driving up the voltage of the spark.  It's entirely possible that I'm wrong though.

mystic_1

[TwoTired]

Excellent TT!

Now, not to derail the thread but he said that the gap determines the voltage (?) Surely the voltage is determined by the primary:secondary ratio of the coils.

No, not in this system.  The coil capability is determined by turns ratio, core size, etc.  But, the peak capability is not necessarily used.  Analogy: You may be able to lift 100lb.  But, your job only requires that lift 50 lbs during your work day, which you do routinely.  You don't need to add another 50 lbs to the normal workload in order to do your routine work.

The ability of the spark to jump the gap depends upon the size of the gap and the properties of the conducting medium (ie the air in this case)

That is correct.  Voltage potential causes the gases between the electrodes to ionize.  When the ionization level reaches the point where the gases turn to plasma, it creates an electrical conductor which electrical current can flow through.

C15: If you have two wires coming from the coil (as well as the HT Lead of course) it shouldn't matter which way round they are connected.

  Not to produce spark.  However, changing polarity does effect some timing light triggers.

You may wish to read a more detailed ignition system description here:
http://forums.sohc4.net/index.php?topic=46186.msg484019#msg484019

Now, not to derail the thread but he said that the gap determines the voltage (?) Surely the voltage is determined by the primary:secondary ratio of the coils. The ability of the spark to jump the gap depends upon the the size of the gap and the properties of the conducting medium (ie the air in this case)

By my understanding, V=IR, so as resistance increases then voltage increases, assuming current remains constant.  So, as the air gap increases, resistance increases, thus driving up the voltage of the spark.  It's entirely possible that I'm wrong though.

mystic_1

There is no current flow until there is an arc present at the electrodes.  So, you can't really apply Ohm's Law to the air gap.  Ionization and plasma formation must occur first.  Then, during the spark event, the actual arc resistance approaches zero.  (Not the entire event, but part of it.)
Note that ohm's law is not universal to all materials.  It works quite well with metal conductors, while noting metal's resistance changes with temperatures.  Plasmas do not obey ohm's law.  They decrease their resistance as the current goes up.

Cheers,

[Soos]

.....

TT... SO technically(completely offtrack here) lightening, or at least what we see of it, is actually a visual light emitted because the air is heated to a plasma state?
And not the actual electricity?

?
Did I miss this one in science class?


Sorry, COOL setup though!



l8r

[TwoTired]

.....

TT... SO technically(completely offtrack here) lightening, or at least what we see of it, is actually a visual light emitted because the air is heated to a plasma state?
And not the actual electricity?

?
Did I miss this one in science class?

Sorry, COOL setup though!

l8r

Lightning entails much of the same process that occurs across the spark plug electrodes, but on a larger scale.  Huge disparities of voltage potential occur, which ionizes the atmosphere between them.  When the ionization level reaches the point where plasma formation can occur, these potentials are equalized through the plasma channel (the lightning bolt).  Heat and light are produced within the channel, and radiated outward while the event occurs.

There's a lot more to say about lightning:
http://en.wikipedia.org/wiki/Lightning

And Plasma:
http://en.wikipedia.org/wiki/Plasma_(physics)

Cheers,

[Soos]

had never thought to read up on it any...
Interesting ended up reading about ion motors.


THNX!



l8r