Dragmaxster
Well-Known Member
Do you think maybe it's the coil itself?
Do you have the denso 129700-4400 (smaller)or the 4800 (longer)?
Do you have the denso 129700-4400 (smaller)or the 4800 (longer)?
Godzilla pooped the bed!
- Thread starter Bill Seward
- Start date
Help Support VMAX Forum:
Bill Seward
Well-Known Member
I've got the longer coils, but find it hard to believe all 4 of them would fail at once - but stranger things have happened..
The bike ran fine and I shut it down the last time it ran.. A day later - nothing.
The bike ran fine and I shut it down the last time it ran.. A day later - nothing.
Dragmaxster
Well-Known Member
Check the ohms on the plugs- should be 2.4-2.6 --- I sold 2 sets last week and i'm making 2 more sets this week.
1 is long (4800) and 1 is shorter (4400).
1 is long (4800) and 1 is shorter (4400).
I had a pick-up coil which went dead after getting hot from running for 15 min. or more. The later model 1990+ ignition, so when it was dead, the bike stopped. Let it cool down, and it would start back up. The flywheel usually only goes bad from some physical thing, like a loose nut since the pieces are embedded into it to generate the field when it's spinning. It's probably the pick-up coil or the wires from it, I dunno, you'd think they test good resistance, it should run though.
As to all four ignition coils going simultaneously bad, your lotto grand prize chances are probably better...
As to all four ignition coils going simultaneously bad, your lotto grand prize chances are probably better...
Dragmaxster
Well-Known Member
This same thing happened to a fellow rider on another site 2 weeks ago- no fire from any coil but everything else lit up--- it was his pick-up coil.If the box sean sent works then it has to be the pick up coils as they are what send the signals to the box that send signals to the coils.
Could he be getting the correct resistance and maybe the pick-up coil is out of place?
Could he be getting the correct resistance and maybe the pick-up coil is out of place?
Bill Seward
Well-Known Member
I would think there would be some expensive noises if the pickup coils moved inside the case. Never heard anything like that. I did check for voltage on the wires running to one of the coil sticks.. Got 11.8 volts with ignition on. I checked resistance at the connector under the seat, and at the TCI box. Seeing that this system generates spark when the voltage is interrupted to coils, and voltage is present constantly at COP, this should really point to a bad pickup, even though the resistance is within spec.. The pulse tells the box to interrupt current to COP, generating the spark. The box I got from Sean didn't work either. This is looking more like a bad pickup coil problem, even though they checked OK on the ohmmeter. I would think I'd get spark from at least one cylinder, unless all coils were bad. How they'd read proper resistance is beyond me..
I'm getting a headache now..
I'm getting a headache now..
![Bovemanx Motorcycle Phone Mount Holder, [150mph Wind Anti-Shake][7.2inch Big Phone Friendly] Bike Phone Holder, Motorcycle Handlebar Cell Phone Clamp, Compatible with iPhone 16 Pro Max Smartphones](https://m.media-amazon.com/images/I/51F+1sontPL._SL500_.jpg)
Dragmaxster
Well-Known Member
I'm saying that because i had a pickup screw come loose and the alignment was off.
Bill Seward
Well-Known Member
Never knew that could happen.. Did all four cylinders go out?
Dragmaxster
Well-Known Member
Yes
Dragmaxster
Well-Known Member
Here is why you have a headache---
This article is much more technical than most people need. Look for another article soon that is easier to understand, if perhaps a little less accurate.
UNDERLYING PRINCIPLES.
What is a Conductor?
When I say conductor it may mean things that we don't normally consider conductors. A conductor is anything that a current flows through. It can be a length of wire, a solid chunk of metal like a frame, air like a spark plug gap, or even empty space like the solar wind.
Currents, Magnetic Fields and Induction.
When current flows through a conductor a magnetic field is created around the conductor. The field is shaped like a cylinder with the conductor at the center. The field is strongest near the conductor and dissipates quickly as you move further away but it theoretically extends to infinity. When a conductor is exposed to a varying magnetic field a voltage is created in the conductor. If the conductor is a continuous circuit, like a loop of wire, the voltage will cause a current to flow in the conductor. This scientific principle is called induction.
Induction in a Circuit.
When an induced voltage causes a current flow in a conductor that current will create a magnetic field of it's own that is opposite to the field it is passing through. This new magnetic field will weaken the existing field. That will reduce the amount of induced voltage and therefore current flow in the conductor compared to what it would be if this effect didn't exist.
Induction With and Without Current Flow.
The important principle is that if no current flows in the conductor then the voltage induced in the conductor will be higher but if current does flow in the conductor then the induced voltage will be lower.
Magnetic Field Energy
When a current flows in a conductor and it generates a magnetic field the magnetic field stores energy. The effect can be thought of as inflating a balloon except the balloon never pops. It can be inflated until the flowing current melts the conductor.
Self Induction.
When a varying current flows in a wire and creates a varying magnetic field any wire that is exposed to the magnetic field will have a voltage generated in itself. This applies even if the wire is the same wire the current is flowing in. For example if you double a wire back on itself and cause a current to flow through the wire the magnetic field created in one point of the wire will intersect the doubled back portion and induce a voltage there. By the same token the doubled back portion will induce a voltage in the first part of the wire. This effect is significant and can not be ignored in many circuits. It is used to produce many beneficial effects but often it is a nuisance and has to be countered. It is called self induction.
Self Induction in a Coil.
If a wire is coiled the magnetic field from each loop will react with every other loop to induce a voltage in the opposite direction to current flow. The strength of this reaction is directly related to the number of turns and the speed with which the current and therefore the magnetic field changes. The more turns there are the more self induction there will be so the greater it's tendency to resist changes in current flow. That means if there are few turns in a coil then when a voltage is applied current will build quickly but if there are many turns then the current will build more slowly.
Induction Between Two Coils.
The more turns there are in a coil the stronger the combined magnetic field will be from all of the turns. If a second coil is near by it will have a voltage induced by the first coil. The more turns of wire there are in the second coil the higher the voltage that will be induce in it. If current flows in the second coil it will create it's own magnetic field. That magnetic field will interfere with the magnetic field from the first coil and will further slow the buildup of current in that coil. If no current flows in the second coil it will not interfere with the first coil even though a voltage is induced in it.
Self Induction Effect.
A consequence of induction is that when no current is flowing it takes some effort to build a current up. When a current is flowing in a system it tends to want to keep flowing. It is the electrical equivalent of inertia. Electricity has almost no actual inertia. Self induction comes from the energy stored in the magnetic field in an inductor. This energy has to be dissipated when the current flow through the inductor changes. This stored energy can be put to good use.
Sources if Induction.
The magnetic field can vary because the magnet and/or the conductor moves. If the magnet is an electromagnet and the current passing through it is changed the magnetic field will vary. If any material that has a magnetic response, like iron, enters or leaves the magnetic field the field will vary. The more the magnetic field varies and the longer the conductor the greater the induced voltage will be.
Multiple Voltages and Currents in a wire.
Finally, a circuit can be acted upon by more than one influence at a time. For example a circuit may have a battery applying 12 volts and an inductor inducing 20 volts at a given instant. The actual voltage acting at a single point will depend on whether the battery and inductor are working together or opposing each other. It will also depend on other components in the system. It can also have currents from many sources flowing through it, even in opposite directions. Of course in physical reality this doesn't actually happen but the theory doesn't care that other devices are using the same piece of wire.
APPLICATION OF PRINCIPLES
What It's All About.
The purpose of an ignition system is to put enough energy into the combustion chamber to start the mixture burning at the proper time. It doesn't do anything else.
Why Induction Matters.
An ignition system relies on induction to get thousands of volts from a 12 volt source. An ignition system has two circuits. The primary circuit and the secondary circuit. The primary circuit works at battery voltage and consists of the trigger mechanism (points cam, magnetic pickup or an LED), a switch (points, or igniter), a power source, some wiring, a ground path through the frame and the primary side of the ignition coil. The secondary circuit is high voltage and consists of the spark plugs, ignition wires with end terminals (except in coil on plug applications), possibly a distributor, the secondary side of the ignition coil and a ground circuit through the engine and frame. The two circuits are mechanically and electrically separate but are connected by a magnetic field in the coil.
The Coil is the Key.
The purpose of the primary windings of the ignition coil is to create a strong magnetic field that envelopes the secondary windings. When the coil is turned on the magnetic field does not build instantly to an infinite level because self induction and the resistance of the wire itself limits how fast 12 volts can build the magnetic field. Because the magnetic field builds relatively slowly it does not induce enough voltage in the secondary windings to arc the gap at the spark plugs. This is important because the coil turns on long before ignition is needed. Since no current flows in the secondary windings of the ignition coil it does not have a magnetic field of it's own during the build-up phase. When the primary windings are turned off current stops flowing in them. With no current flowing in either winding the magnetic field starts to collapse very quickly. Hundreds of volts are induced in the primary windings but the switch that turned the coil off is designed to resist this so still no current flows in the primary winding. Since the secondary winding has several times as many turns as the primary winding so thousands of volts are induced in it. That is sufficient to arc the spark plug gaps and the ignition fires. Current either flows in the primary winding or the secondary winding but never in both at the same time unless there is a problem.
ACTUAL DEVICES
Pickup Coil
In our ignition systems the primary side of the ignition system is triggered by a magnetic pickup mounted near the starter clutch. It consists of a magnet and a coil of wire. When a metallic irregularity on the starter clutch passes by the pickup the magnetic field that is already there is changed by the presence of additional magnetizable material. The changing magnetic field induces a voltage in the coil of wire in the pickup. That voltage is carried by wires to the igniter. A small amount of current also flows to the igniter but it is negligible.
Igniter
The igniter is a solid state switch. All it does is turn on/off 12 volts to the ignition coil. It incorporates circuitry to calculate a timing delay from the time it gets a signal from the pickup coil. It does the delay to effect appropriate ignition timing. It replaces points and centrifugal advance. On other engines it may also receive information from the ECM or sensors that it would use in it's calculations. Our igniters also calculate a turn time so that the coil is on long enough to become fully charged but not so long that it overheats. The igniter may also incorporate a current limiting circuit to further protect the coil from burning up.
Ignition coil
Our ignition coils are composed of two coils of wire, primary and secondary. One end of the primary wire is connected to battery power. The other end goes to ground through the igniter. This allows the igniter to control the coil. The primary coil has several hundred turns of relatively thick wire. The secondary coil has several thousand turns of wire that is relatively thin. The ends of the secondary windings are connected to two coil wires and then to the spark plugs.
Interaction of the Igniter and Coil
When the igniter turns the coil on current starts to flow in the primary coil. The primary winding of the coil has low resistance. If the current was allowed to build for too long it would reach a level that the coil couldn't sustain. The coil would burn up. To prevent this the igniter delays turning the coil on until there is just enough time to fully charge. As the current builds in the primary coil it induces a voltage in the secondary coil. Since the secondary coil has a lot more turns the voltage is much higher. Self inductance limits the speed at which the magnetic field builds so that the induced voltage in the secondary coil isn't enough to jump the spark plug gap. No current flows in the secondary circuit yet.
Primary Induction
When the igniter stops current flow in the primary circuit the magnetic field the current has generated collapses. When it does this it cuts through the windings of the primary coil. In doing so it generates a voltage that tries to keep the current flowing. It is pretty effective at this and several hundred volts can be generated in the primary circuit. This high voltage has to be resisted by the igniter. It takes some good components to handle this but they are designed to do it and mostly succeed.
Secondary Ignition - Fire!
When the igniter stops current flow in the primary circuit the collapsing magnetic field also generates voltage in the secondary windings. In this case it is on the order of 5000-7000 volts and most coils can go a lot higher if necessary. That is sufficient to start an arc across both spark plugs. Once the arc is established it is much easier to maintain so the voltage drops below 3000 volts. As current flows through the secondary windings it creates it's own magnetic field that supports the existing magnetic field. The more current that flows the more support the magnetic field gets and the slower it collapses. If the ignition wires are shorted to ground and there is no resistance in the circuit the magnetic field will collapse very slowly. If the spark plugs have large gaps and there is a lot of resistance in the secondary circuit then the field will collapse faster. This will mean less arc time. Keep this in mind because shortly I'm going to tell you just the opposite.
Energy Management.
If you think about it you will realize that anything that takes energy from the system causes faster field collapse because that is the source of the energy. The faster the energy drains away the less time the arc will be available to ignite the mixture.
Where the Energy Goes.
In real ignition systems there is no such thing a no resistance. If the ignition wires are shorted to ground they will still have some resistance. The windings in the coil secondary will also have resistance. Even the engine and frame will have resistance. There will always be something to absorb the energy of the magnetic field. The trick is to manage where the energy goes so that enough gets to the combustion chamber to ignite the mixture. The arc has to be intense enough to cause ignition and last long enough that the momentary presence of a too lean or too rich pocket of mixture at the spark plug won't produce a misfire.
The Energy Flow Curve or The Brain Straining Part.
There will be an amount of resistance that will consume energy the fastest. More or less resistance will consume energy slower. The exact resistance for maximum absorption will depend on many things in the system but it is so low that in practice it is never achieved. Real ignitions already have so much secondary resistance that they are already well above the level where energy would be used the fastest. When more resistance is intentionally added the current flow will be reduced. Voltage will also increase but the biggest voltage limiter is the spark plug gaps. Since that is fairly stable once the arc has been established the voltage doesn't increase proportionally to the current decrease. The total energy removed from the system will go down. Arc time will go up but arc intensity will go down. It is important in designing an ignition system to not trade off too much time for intensity or vice-a-versa. Fortunately there is a lot of room for trading.
Whither Resistance?
From an electrical standpoint it makes little difference where in the secondary circuit additional resistance is located. From a practical standpoint it can be important. I don't know why resistance ignition wires were created but in my mind it is the worst place to put resistance. The fact that wires with 3000 ohms / foot resistance can work on an engine with wires anywhere from 6" to 6' long proves that there is a lot of reserve capacity in most ignition systems. I think the resistance belongs in hard parts where it can be the same for each cylinder but not in the spark plugs. Putting it in the plugs costs something. It's not a lot but plugs get changed more often than other parts so why make them any more expensive. My opinion is that the spark plug cap is a great place to put the resistance. Inside the coil wouldn't be bad either as long as it didn't make the coil more failure prone.
SOME PRACTICAL CONSIDERATIONS.
Interference
When any coil is energized or de-energized it will self induce and a voltage spike will be created. There are several ways to combat this if it isn't wanted. All systems with large inductors have circuit protection devices built in. All of the countermeasures have limitations though so voltage spikes are always being introduced into electrical systems with inductors. Mostly they are attenuated enough by the protection devices that they don't cause problems. The largest inductor on a motor vehicle is the ignition coil. As I stated above it can create a voltage spike in the hundreds of volts. If it isn't controlled it can do nasty things to sensitive electronics. Motor vehicle electronics have to be designed to withstand the remnants of these spikes.
A properly functioning igniter is designed from the start to resist the worst spikes a coil can produce. Many will even withstand an arc from the secondary winding. Our ignitions are made from components produce 30 years ago. If one thing has advanced in the last 30 years it is electronics. Age hasn't improved our old electronics either. What we rely on is of much lower quality than what is available today. It is to be expected that as time goes by some spikes will start to leak through. Not just because our igniters are getting weaker but because other components are putting out more noise. It's hard to tell if a problem is actually a failed module or some other some other device that has gotten out of hand. This situation can be pretty hard to diagnose correctly. The good news is that we now have available modern igniters to fit our old machines.
Another source of interference could be the pickups. They produce fairly weak signals at cranking speeds so the igniters have to be very sensitive. In that situation it could be possible for stray signals to be intercepted by the pickup leads and interpreted by the igniter as a signal to fire. I think this is highly unlikely though. The pickup coil is only connected to the igniter. It does not interface directly with any other circuit. The only interference it could receive would be from radio waves intercepting the pickup leads. The signal from an antenna, which is what we are talking about, is measured in femtowatts. That's quadrillionths of a watt. Pickup coils even at idle generate hundredths of a watt. I just don't see how it would work. More likely would be a short to ground or power or an intermittent open circuit that would cause trouble. And that's just wiring, not interference.
There used to be a lot of talk about not running ignition wires parallel to each other because they could induce a spark in each other that would cause a misfire. That idea has long been disproved. These days everybody bundles ignition wires close together and there is no problem. I'm avoiding math here but if we did the math it would totally disprove the idea of inductive crossfire.
Ground circuits can cause all kinds of mystifying situations. If the ground side of the igniter was corroded or the ground of some other component was bad and it was trying to find ground through the igniter then that could be the source of a problem. A common problem is at the battery ground cable and its connections. Every system's power runs through the battery ground until the charging system comes on line. During cranking a lot of current flows through the starter to the frame and then through the battery ground cable to get back to the battery. If the ground cable is in poor condition it may conduct enough power to run the starter but everything else will not be able to pass the current needed to run. This can lead to a no start condition due to no spark.
Conclusion.
A lot of different ways have been found to start a fire inside a cylinder but induction based systems seem to do the job best. Understanding what each part of the system does can be useful in diagnosing problems.
This article is much more technical than most people need. Look for another article soon that is easier to understand, if perhaps a little less accurate.
UNDERLYING PRINCIPLES.
What is a Conductor?
When I say conductor it may mean things that we don't normally consider conductors. A conductor is anything that a current flows through. It can be a length of wire, a solid chunk of metal like a frame, air like a spark plug gap, or even empty space like the solar wind.
Currents, Magnetic Fields and Induction.
When current flows through a conductor a magnetic field is created around the conductor. The field is shaped like a cylinder with the conductor at the center. The field is strongest near the conductor and dissipates quickly as you move further away but it theoretically extends to infinity. When a conductor is exposed to a varying magnetic field a voltage is created in the conductor. If the conductor is a continuous circuit, like a loop of wire, the voltage will cause a current to flow in the conductor. This scientific principle is called induction.
Induction in a Circuit.
When an induced voltage causes a current flow in a conductor that current will create a magnetic field of it's own that is opposite to the field it is passing through. This new magnetic field will weaken the existing field. That will reduce the amount of induced voltage and therefore current flow in the conductor compared to what it would be if this effect didn't exist.
Induction With and Without Current Flow.
The important principle is that if no current flows in the conductor then the voltage induced in the conductor will be higher but if current does flow in the conductor then the induced voltage will be lower.
Magnetic Field Energy
When a current flows in a conductor and it generates a magnetic field the magnetic field stores energy. The effect can be thought of as inflating a balloon except the balloon never pops. It can be inflated until the flowing current melts the conductor.
Self Induction.
When a varying current flows in a wire and creates a varying magnetic field any wire that is exposed to the magnetic field will have a voltage generated in itself. This applies even if the wire is the same wire the current is flowing in. For example if you double a wire back on itself and cause a current to flow through the wire the magnetic field created in one point of the wire will intersect the doubled back portion and induce a voltage there. By the same token the doubled back portion will induce a voltage in the first part of the wire. This effect is significant and can not be ignored in many circuits. It is used to produce many beneficial effects but often it is a nuisance and has to be countered. It is called self induction.
Self Induction in a Coil.
If a wire is coiled the magnetic field from each loop will react with every other loop to induce a voltage in the opposite direction to current flow. The strength of this reaction is directly related to the number of turns and the speed with which the current and therefore the magnetic field changes. The more turns there are the more self induction there will be so the greater it's tendency to resist changes in current flow. That means if there are few turns in a coil then when a voltage is applied current will build quickly but if there are many turns then the current will build more slowly.
Induction Between Two Coils.
The more turns there are in a coil the stronger the combined magnetic field will be from all of the turns. If a second coil is near by it will have a voltage induced by the first coil. The more turns of wire there are in the second coil the higher the voltage that will be induce in it. If current flows in the second coil it will create it's own magnetic field. That magnetic field will interfere with the magnetic field from the first coil and will further slow the buildup of current in that coil. If no current flows in the second coil it will not interfere with the first coil even though a voltage is induced in it.
Self Induction Effect.
A consequence of induction is that when no current is flowing it takes some effort to build a current up. When a current is flowing in a system it tends to want to keep flowing. It is the electrical equivalent of inertia. Electricity has almost no actual inertia. Self induction comes from the energy stored in the magnetic field in an inductor. This energy has to be dissipated when the current flow through the inductor changes. This stored energy can be put to good use.
Sources if Induction.
The magnetic field can vary because the magnet and/or the conductor moves. If the magnet is an electromagnet and the current passing through it is changed the magnetic field will vary. If any material that has a magnetic response, like iron, enters or leaves the magnetic field the field will vary. The more the magnetic field varies and the longer the conductor the greater the induced voltage will be.
Multiple Voltages and Currents in a wire.
Finally, a circuit can be acted upon by more than one influence at a time. For example a circuit may have a battery applying 12 volts and an inductor inducing 20 volts at a given instant. The actual voltage acting at a single point will depend on whether the battery and inductor are working together or opposing each other. It will also depend on other components in the system. It can also have currents from many sources flowing through it, even in opposite directions. Of course in physical reality this doesn't actually happen but the theory doesn't care that other devices are using the same piece of wire.
APPLICATION OF PRINCIPLES
What It's All About.
The purpose of an ignition system is to put enough energy into the combustion chamber to start the mixture burning at the proper time. It doesn't do anything else.
Why Induction Matters.
An ignition system relies on induction to get thousands of volts from a 12 volt source. An ignition system has two circuits. The primary circuit and the secondary circuit. The primary circuit works at battery voltage and consists of the trigger mechanism (points cam, magnetic pickup or an LED), a switch (points, or igniter), a power source, some wiring, a ground path through the frame and the primary side of the ignition coil. The secondary circuit is high voltage and consists of the spark plugs, ignition wires with end terminals (except in coil on plug applications), possibly a distributor, the secondary side of the ignition coil and a ground circuit through the engine and frame. The two circuits are mechanically and electrically separate but are connected by a magnetic field in the coil.
The Coil is the Key.
The purpose of the primary windings of the ignition coil is to create a strong magnetic field that envelopes the secondary windings. When the coil is turned on the magnetic field does not build instantly to an infinite level because self induction and the resistance of the wire itself limits how fast 12 volts can build the magnetic field. Because the magnetic field builds relatively slowly it does not induce enough voltage in the secondary windings to arc the gap at the spark plugs. This is important because the coil turns on long before ignition is needed. Since no current flows in the secondary windings of the ignition coil it does not have a magnetic field of it's own during the build-up phase. When the primary windings are turned off current stops flowing in them. With no current flowing in either winding the magnetic field starts to collapse very quickly. Hundreds of volts are induced in the primary windings but the switch that turned the coil off is designed to resist this so still no current flows in the primary winding. Since the secondary winding has several times as many turns as the primary winding so thousands of volts are induced in it. That is sufficient to arc the spark plug gaps and the ignition fires. Current either flows in the primary winding or the secondary winding but never in both at the same time unless there is a problem.
ACTUAL DEVICES
Pickup Coil
In our ignition systems the primary side of the ignition system is triggered by a magnetic pickup mounted near the starter clutch. It consists of a magnet and a coil of wire. When a metallic irregularity on the starter clutch passes by the pickup the magnetic field that is already there is changed by the presence of additional magnetizable material. The changing magnetic field induces a voltage in the coil of wire in the pickup. That voltage is carried by wires to the igniter. A small amount of current also flows to the igniter but it is negligible.
Igniter
The igniter is a solid state switch. All it does is turn on/off 12 volts to the ignition coil. It incorporates circuitry to calculate a timing delay from the time it gets a signal from the pickup coil. It does the delay to effect appropriate ignition timing. It replaces points and centrifugal advance. On other engines it may also receive information from the ECM or sensors that it would use in it's calculations. Our igniters also calculate a turn time so that the coil is on long enough to become fully charged but not so long that it overheats. The igniter may also incorporate a current limiting circuit to further protect the coil from burning up.
Ignition coil
Our ignition coils are composed of two coils of wire, primary and secondary. One end of the primary wire is connected to battery power. The other end goes to ground through the igniter. This allows the igniter to control the coil. The primary coil has several hundred turns of relatively thick wire. The secondary coil has several thousand turns of wire that is relatively thin. The ends of the secondary windings are connected to two coil wires and then to the spark plugs.
Interaction of the Igniter and Coil
When the igniter turns the coil on current starts to flow in the primary coil. The primary winding of the coil has low resistance. If the current was allowed to build for too long it would reach a level that the coil couldn't sustain. The coil would burn up. To prevent this the igniter delays turning the coil on until there is just enough time to fully charge. As the current builds in the primary coil it induces a voltage in the secondary coil. Since the secondary coil has a lot more turns the voltage is much higher. Self inductance limits the speed at which the magnetic field builds so that the induced voltage in the secondary coil isn't enough to jump the spark plug gap. No current flows in the secondary circuit yet.
Primary Induction
When the igniter stops current flow in the primary circuit the magnetic field the current has generated collapses. When it does this it cuts through the windings of the primary coil. In doing so it generates a voltage that tries to keep the current flowing. It is pretty effective at this and several hundred volts can be generated in the primary circuit. This high voltage has to be resisted by the igniter. It takes some good components to handle this but they are designed to do it and mostly succeed.
Secondary Ignition - Fire!
When the igniter stops current flow in the primary circuit the collapsing magnetic field also generates voltage in the secondary windings. In this case it is on the order of 5000-7000 volts and most coils can go a lot higher if necessary. That is sufficient to start an arc across both spark plugs. Once the arc is established it is much easier to maintain so the voltage drops below 3000 volts. As current flows through the secondary windings it creates it's own magnetic field that supports the existing magnetic field. The more current that flows the more support the magnetic field gets and the slower it collapses. If the ignition wires are shorted to ground and there is no resistance in the circuit the magnetic field will collapse very slowly. If the spark plugs have large gaps and there is a lot of resistance in the secondary circuit then the field will collapse faster. This will mean less arc time. Keep this in mind because shortly I'm going to tell you just the opposite.
Energy Management.
If you think about it you will realize that anything that takes energy from the system causes faster field collapse because that is the source of the energy. The faster the energy drains away the less time the arc will be available to ignite the mixture.
Where the Energy Goes.
In real ignition systems there is no such thing a no resistance. If the ignition wires are shorted to ground they will still have some resistance. The windings in the coil secondary will also have resistance. Even the engine and frame will have resistance. There will always be something to absorb the energy of the magnetic field. The trick is to manage where the energy goes so that enough gets to the combustion chamber to ignite the mixture. The arc has to be intense enough to cause ignition and last long enough that the momentary presence of a too lean or too rich pocket of mixture at the spark plug won't produce a misfire.
The Energy Flow Curve or The Brain Straining Part.
There will be an amount of resistance that will consume energy the fastest. More or less resistance will consume energy slower. The exact resistance for maximum absorption will depend on many things in the system but it is so low that in practice it is never achieved. Real ignitions already have so much secondary resistance that they are already well above the level where energy would be used the fastest. When more resistance is intentionally added the current flow will be reduced. Voltage will also increase but the biggest voltage limiter is the spark plug gaps. Since that is fairly stable once the arc has been established the voltage doesn't increase proportionally to the current decrease. The total energy removed from the system will go down. Arc time will go up but arc intensity will go down. It is important in designing an ignition system to not trade off too much time for intensity or vice-a-versa. Fortunately there is a lot of room for trading.
Whither Resistance?
From an electrical standpoint it makes little difference where in the secondary circuit additional resistance is located. From a practical standpoint it can be important. I don't know why resistance ignition wires were created but in my mind it is the worst place to put resistance. The fact that wires with 3000 ohms / foot resistance can work on an engine with wires anywhere from 6" to 6' long proves that there is a lot of reserve capacity in most ignition systems. I think the resistance belongs in hard parts where it can be the same for each cylinder but not in the spark plugs. Putting it in the plugs costs something. It's not a lot but plugs get changed more often than other parts so why make them any more expensive. My opinion is that the spark plug cap is a great place to put the resistance. Inside the coil wouldn't be bad either as long as it didn't make the coil more failure prone.
SOME PRACTICAL CONSIDERATIONS.
Interference
When any coil is energized or de-energized it will self induce and a voltage spike will be created. There are several ways to combat this if it isn't wanted. All systems with large inductors have circuit protection devices built in. All of the countermeasures have limitations though so voltage spikes are always being introduced into electrical systems with inductors. Mostly they are attenuated enough by the protection devices that they don't cause problems. The largest inductor on a motor vehicle is the ignition coil. As I stated above it can create a voltage spike in the hundreds of volts. If it isn't controlled it can do nasty things to sensitive electronics. Motor vehicle electronics have to be designed to withstand the remnants of these spikes.
A properly functioning igniter is designed from the start to resist the worst spikes a coil can produce. Many will even withstand an arc from the secondary winding. Our ignitions are made from components produce 30 years ago. If one thing has advanced in the last 30 years it is electronics. Age hasn't improved our old electronics either. What we rely on is of much lower quality than what is available today. It is to be expected that as time goes by some spikes will start to leak through. Not just because our igniters are getting weaker but because other components are putting out more noise. It's hard to tell if a problem is actually a failed module or some other some other device that has gotten out of hand. This situation can be pretty hard to diagnose correctly. The good news is that we now have available modern igniters to fit our old machines.
Another source of interference could be the pickups. They produce fairly weak signals at cranking speeds so the igniters have to be very sensitive. In that situation it could be possible for stray signals to be intercepted by the pickup leads and interpreted by the igniter as a signal to fire. I think this is highly unlikely though. The pickup coil is only connected to the igniter. It does not interface directly with any other circuit. The only interference it could receive would be from radio waves intercepting the pickup leads. The signal from an antenna, which is what we are talking about, is measured in femtowatts. That's quadrillionths of a watt. Pickup coils even at idle generate hundredths of a watt. I just don't see how it would work. More likely would be a short to ground or power or an intermittent open circuit that would cause trouble. And that's just wiring, not interference.
There used to be a lot of talk about not running ignition wires parallel to each other because they could induce a spark in each other that would cause a misfire. That idea has long been disproved. These days everybody bundles ignition wires close together and there is no problem. I'm avoiding math here but if we did the math it would totally disprove the idea of inductive crossfire.
Ground circuits can cause all kinds of mystifying situations. If the ground side of the igniter was corroded or the ground of some other component was bad and it was trying to find ground through the igniter then that could be the source of a problem. A common problem is at the battery ground cable and its connections. Every system's power runs through the battery ground until the charging system comes on line. During cranking a lot of current flows through the starter to the frame and then through the battery ground cable to get back to the battery. If the ground cable is in poor condition it may conduct enough power to run the starter but everything else will not be able to pass the current needed to run. This can lead to a no start condition due to no spark.
Conclusion.
A lot of different ways have been found to start a fire inside a cylinder but induction based systems seem to do the job best. Understanding what each part of the system does can be useful in diagnosing problems.
Yep....only slightly technical. ....
Sent from my SCH-R890 using Tapatalk
Sent from my SCH-R890 using Tapatalk
Bill Seward
Well-Known Member
Now my teeth hurt...
Bill Seward
Well-Known Member
Gonna swap out the pickups next.
Dragmaxster
Well-Known Member
+1
I'll bet that's it.
I'll bet that's it.
Dorney
Well-Known Member
Hi Bill
Did you try unplugging the kickstand relay behind the left side scoop ? It is right by the fan plug & horn wires. I had the same problem & that's what it was. Unplugged it & it fired right up.
Dave
Did you try unplugging the kickstand relay behind the left side scoop ? It is right by the fan plug & horn wires. I had the same problem & that's what it was. Unplugged it & it fired right up.
Dave
Bill Seward
Well-Known Member
Got an email this morning from Sean with the same suggestion..
SUCCESS! Godzilla Lives!!
Lookout Tokyo, Godzillas back!
Thanks toSteve, Sean, and all who gave advice!
Never even knew that little bugge rwas there..
SUCCESS! Godzilla Lives!!
Lookout Tokyo, Godzillas back!
Thanks toSteve, Sean, and all who gave advice!
Never even knew that little bugge rwas there..
Dragmaxster
Well-Known Member
So it was the pickups?
No, the relay for the sidestand switch.
Dragmaxster
Well-Known Member
Any idea why that would cut the fire to the coils?
Mine would start and run but when i put it in gear it would die instantly-same problem with sidestand plug but the wire coming from the sidestand.
Mine would start and run but when i put it in gear it would die instantly-same problem with sidestand plug but the wire coming from the sidestand.
It's a safety switch.....that way you can't take off with the side stand down.
Sent from my SCH-R890 using Tapatalk
Sent from my SCH-R890 using Tapatalk
