Your thoughts on When to change spark plugs?

[Isopedella]

Microns? That's a measurement of distance. I assume you're kidding!

:thumbup: Yep. Tiny. Down to Micro-Poofteenths. Which is "Some Downunder Stuff" and an accepted and recognized unit of measurement.

Also very much tongue in cheek....

As it appears its being asked for an exact measurement and not a range of acceptable ohms.

 

[BajaRon]

:thumbup: Yep. Tiny. Down to Micro-Poofteenths. Which is "Some Downunder Stuff" and an accepted and recognized unit of measurement.

Also very much tongue in cheek....

As it appears its being asked for an exact measurement and not a range of acceptable ohms.

I am not well versed on 'Down Under' terminology. But I like Spiders, so you're good with me!

 

[PMK]

I have replaced many spark plugs due to misfires and engine roughness. This tool in the link is one we use as needed in the aviation industry.
https://www.aircraftspruce.com/catalog/topages/tempestat5k.php

We also still clean by grit blasting (only the inexpensive massive electrode styles), set plug gaps, and “bomb” test each spark plug to witness proper firing while under pressure. This machine allows that.

https://www.aircraftspruce.com/cata...T4b4G1HI1g2pBoD2vbHYdxWNr1KJ3Xz4aAjVNEALw_wcB

Cheap aircraft spark plugs, massive electrode style with no exotic metals run about $40 per spark plug. Two spark plugs per cylinder, so on a common 4 or 6 cylinder engine, 8 or 12 plugs. Double that for a piston twin engine aircraft.

Those inexpensive spark plugs, depending upon the performance level of the engine, last from 150 hours use to about 500 hours until the electrodes are worn to or beyond acceptable limits.

The high performance spark plugs for aircraft are typically iridium electrodes to reduce wear and erosion. Those spark plugs run about $100 or more per spark plug, depending upon where you get them. So not uncommon to spend $2400 on just spark plugs for a high performance twin.

The expensive spark plugs almost always are replaced from a failed resistor. The electrodes show very little or no wear. Simply use wears out the carbon resistor, rendering the spark plug unable to fire during use. In those cases, the misfire, most times is found early, and worse issues do not arise. In situations where the misfire was allowed to continue (dumb pilot or over water operation), the misfire can ruin the shielded spark plug lead, or even carbon track the magnetos distributor block, causing cross firing a different spark plug / cylinder at the wrong time.

Regarding Spyder spark plugs, they are not expensive. The 1330 uses a COP design, and as spark plugs age, the coils can become overloaded and internally fail. In extreme cases of failing spark plugs with a COP setup, a quality coil will not fail, but the discharge will burn thru the spark plug boot, finding the lazy path to ground, going around the spark plug, since that requires a huge effort with a failed spark plug resistor.

In simple terms, modern technology has given us spark plugs with exotic metals and electrodes that do not wear or erode away. In typical fashion though, the least expensive item in assembling a spark plug is the carbon resistor, and that least expensive item causes the issues.

Old school visually inspecting spark plug wear is no longer an option. Manufacturers test and know expected life of a spark plug before damage occurs to other more expensive items. Modern technology requires modern maintenance. Plugs are cheap.

 

[BajaRon]

I have replaced many spark plugs due to misfires and engine roughness. This tool in the link is one we use as needed in the aviation industry.
https://www.aircraftspruce.com/catalog/topages/tempestat5k.php

We also still clean by grit blasting (only the inexpensive massive electrode styles), set plug gaps, and “bomb” test each spark plug to witness proper firing while under pressure. This machine allows that.

https://www.aircraftspruce.com/cata...T4b4G1HI1g2pBoD2vbHYdxWNr1KJ3Xz4aAjVNEALw_wcB

Cheap aircraft spark plugs, massive electrode style with no exotic metals run about $40 per spark plug. Two spark plugs per cylinder, so on a common 4 or 6 cylinder engine, 8 or 12 plugs. Double that for a piston twin engine aircraft.

Those inexpensive spark plugs, depending upon the performance level of the engine, last from 150 hours use to about 500 hours until the electrodes are worn to or beyond acceptable limits.

The high performance spark plugs for aircraft are typically iridium electrodes to reduce wear and erosion. Those spark plugs run about $100 or more per spark plug, depending upon where you get them. So not uncommon to spend $2400 on just spark plugs for a high performance twin.

The expensive spark plugs almost always are replaced from a failed resistor. The electrodes show very little or no wear. Simply use wears out the carbon resistor, rendering the spark plug unable to fire during use. In those cases, the misfire, most times is found early, and worse issues do not arise. In situations where the misfire was allowed to continue (dumb pilot or over water operation), the misfire can ruin the shielded spark plug lead, or even carbon track the magnetos distributor block, causing cross firing a different spark plug / cylinder at the wrong time.

Regarding Spyder spark plugs, they are not expensive. The 1330 uses a COP design, and as spark plugs age, the coils can become overloaded and internally fail. In extreme cases of failing spark plugs with a COP setup, a quality coil will not fail, but the discharge will burn thru the spark plug boot, finding the lazy path to ground, going around the spark plug, since that requires a huge effort with a failed spark plug resistor.

In simple terms, modern technology has given us spark plugs with exotic metals and electrodes that do not wear or erode away. In typical fashion though, the least expensive item in assembling a spark plug is the carbon resistor, and that least expensive item causes the issues.

Old school visually inspecting spark plug wear is no longer an option. Manufacturers test and know expected life of a spark plug before damage occurs to other more expensive items. Modern technology requires modern maintenance. Plugs are cheap.

Good information. We've had to replace a few coils. Almost always associated with a deteriorating spark plug. The Iridium plugs can look great on the outside. As PMK states, it's the internals that tend to fail. Some report going a lot further than the recommended 28k. And I would say 28k is probably low mileage on the current spark plugs. But the next scheduled interval is 56k. And that can tend to be a bridge too far. At least for 1 of the 3 plugs in a 1330. In my unscientific opinion, a lot depends on temperatures and RPM the plug runs at.

 

[BLUEKNIGHT911]

Good information. We've had to replace a few coils. Almost always associated with a deteriorating spark plug. The Iridium plugs can look great on the outside. As PMK states, it's the internals that tend to fail. Some report going a lot further than the recommended 28k. And I would say 28k is probably low mileage on the current spark plugs. But the next scheduled interval is 56k. And that can tend to be a bridge too far. At least for 1 of the 3 plugs in a 1330. In my unscientific opinion, a lot depends on temperatures and RPM the plug runs at.

I said this earlier in this thread..... MY 14 RT now has over 77,000 miles on the OEM plugs..... But I am going to try and change them this winter...... Mike :thumbup:

 

[Cobwebs]

I said this earlier in this thread..... MY 14 RT now has over 77,000 miles on the OEM plugs..... But I am going to try and change them this winter...... Mike :thumbup:

Would be interesting to check the resistance when you pull them out Mike. Also if you notice any difference with the new'uns.

 

[BajaRon]

I said this earlier in this thread..... MY 14 RT now has over 77,000 miles on the OEM plugs..... But I am going to try and change them this winter...... Mike :thumbup:

Do you intend to do the work yourself? We've developed some shortcuts which reduce the time and effort needed for this service. We intend to do a video, but just haven't yet.

 

[BLUEKNIGHT911]

Yes, I'm going to try ..... annnnnnnnnnnnnnnnnnnnnnnnd I will be sending in an order in to you soon .....Mike :thumbup: ...... also will do a resistance check on the old plugs ....Mike

 

[BajaRon]

Yes, I'm going to try ..... annnnnnnnnnnnnnnnnnnnnnnnd I will be sending in an order in to you soon .....Mike :thumbup: ...... also will do a resistance check on the old plugs ....Mike

If you agree to do a full report, I'll send you a set at no charge. I'm interested in what you find. Just PM me your address.

 

[IdahoMtnSpyder]

Just exactly what is the role of resistance in assessing the health of a spark plug? The only unwanted resistance I can fathom is between the electrode and the outer metal body of the plug. So is this a case of if that resistance drops low, i.e., approaching a short circuit condition, the coil has to put out more current than it maybe is designed for? We're looking at a parallel electrical circuit, the shorting path to ground and path through the plug gap so the total current is the sum of that which goes through each path.

I know from a test I did in college engineering lab when capacitive-discharge ignition modules were the fad back in the 60's, that the voltage applied to the electrode rises only to the point where current jumps the gap. If that happens at 10,000 volts, let's say, that is all the higher the voltage will rise to even if the coil is capable of putting out 50,000 volts. As I see it the only purpose of the built-in resistance in the plug electrode is to suppress the total milliamps (microamps?) of current that can flow through the plug when the spark jumps the gap.

Am I missing something?

 

[BajaRon]

Just exactly what is the role of resistance in assessing the health of a spark plug? The only unwanted resistance I can fathom is between the electrode and the outer metal body of the plug. So is this a case of if that resistance drops low, i.e., approaching a short circuit condition, the coil has to put out more current than it maybe is designed for? We're looking at a parallel electrical circuit, the shorting path to ground and path through the plug gap so the total current is the sum of that which goes through each path.

I know from a test I did in college engineering lab when capacitive-discharge ignition modules were the fad back in the 60's, that the voltage applied to the electrode rises only to the point where current jumps the gap. If that happens at 10,000 volts, let's say, that is all the higher the voltage will rise to even if the coil is capable of putting out 50,000 volts. As I see it the only purpose of the built-in resistance in the plug electrode is to suppress the total milliamps (microamps?) of current that can flow through the plug when the spark jumps the gap.

Am I missing something?

Resistance is designed to suppress EMI and RFI. Actually the 1st one covers pretty much everything. RFI is Radio Frequency Interference, which is a specific band of EMI (Electro Magnetic Interference). When the magnetic field collapses, it sends out radiation which can interfere with any kind of electronic signal, like radios, computers, etc. The correct amount of resistance suppresses this action. More resistance increases the load on the coils. Too much load heats them above operating temperature and can cause the coil to fail over time.

Most OEM wires use carbon impregnated fiber to carry the spark and provide resistance. This is an inexpensive way to produce wires but creates a very high resistance factor and it is subject to degradation with heat and vibration. As these wires degrade, resistance increases to the point where the spark may find an easier path and start arcing to metal components near the wire.

 

[Cobwebs]

If you agree to do a full report, I'll send you a set at no charge. I'm interested in what you find. Just PM me your address.

Carefull Mike, read the hair and makeup clause before signing.opcorn:

 

[Knizar]

If you agree to do a full report, I'll send you a set at no charge. I'm interested in what you find. Just PM me your address.

WOW, Go Mike Go! You have about 3 months before riding season.

I'm very interested to hear how 70+K mile plugs check out after 9+ years in use.
Get Ur Done Mike.

:thumbup: Bill

 

[PMK]

Regarding coil failures. A fouled plug, will not destroy a coil. Simply, the energy travels to ground. A normal operation of a good plug, yes, the voltage required to fire the spark plug is determined by various factors. Compression ratio, BMEP, ignition timing, resistance of the plug, spark plug wire condition, resistance of the ground circuit, and more.

No doubt heat is bad for ignition coils, that heat will alter the resistance of primary and secondary segments of the coil itself.

Electronic ignitions, even battery ignitions or magnetos, do not like a high resistance or open high tension circuit. As resistance increases, the coils energy does best to be discharged. As resistance increases, the coil secondary windings can try to jump to the coils laminations. Other times, the windings will energize as the field collapses, and the path of least resistance will jump windings within the coil. Also, with these new COP setups, typically the plug resides in a deep cavity. There is a very short boot between to coil and plug. Since the boots position is between the resistor and coil, the misfire can deteriorate the rubber boot, burning it, and then misfiring to the metal ground of the cylinder head.

Regarding testing the plugs for resistance, typically the resistor is a carbon / graphite conductive material. Most commonly for powersports applications, that require resistor spark plugs, the value when new is 5-6 k ohms.

I have dealt with vintage motorcycle ignition issues, where 5k ohm spark plug caps had the carbon resistor ohm value increase to over 10k ohms. The higher resistance of the plug cap prevented the plug from firing at all. Swap the cap and starts in one kick.

We also deal with, and this is a serious problem, most of the spark plug manufacturers in the industry have stopped making non resistor plugs. Some owners, unaware there is a difference, have installed resistor plugs in ignitions not designed for them. Doing so results in various issues, most often, the ignition does not fire the plug, and in some cases, ruins ignition components.

 

[BLUEKNIGHT911]

WOW, Go Mike Go! You have about 3 months before riding season.

I'm very interested to hear how 70+K mile plugs check out after 9+ years in use.
Get Ur Done Mike.

:thumbup: Bill

Well about the mileage .....I made a mis-take :dontknow: ..... I actually have 80,626 ( it's been in my basement since Nov. awaiting a Full service including an HCM filter ) ..... So yes it's 70,000 + 10,626 = 80,626 mi....... Thanks for your offer Ron ..... I'll get in touch with you soon .....Mike :thumbup:

 

[BLUEKNIGHT911]

Regarding coil failures. A fouled plug, will not destroy a coil. Simply, the energy travels to ground. A normal operation of a good plug, yes, the voltage required to fire the spark plug is determined by various factors. Compression ratio, BMEP, ignition timing, resistance of the plug, spark plug wire condition, resistance of the ground circuit, and more.

No doubt heat is bad for ignition coils, that heat will alter the resistance of primary and secondary segments of the coil itself.

Electronic ignitions, even battery ignitions or magnetos, do not like a high resistance or open high tension circuit. As resistance increases, the coils energy does best to be discharged. As resistance increases, the coil secondary windings can try to jump to the coils laminations. Other times, the windings will energize as the field collapses, and the path of least resistance will jump windings within the coil. Also, with these new COP setups, typically the plug resides in a deep cavity. There is a very short boot between to coil and plug. Since the boots position is between the resistor and coil, the misfire can deteriorate the rubber boot, burning it, and then misfiring to the metal ground of the cylinder head.

Regarding testing the plugs for resistance, typically the resistor is a carbon / graphite conductive material. Most commonly for powersports applications, that require resistor spark plugs, the value when new is 5-6 k ohms.

I have dealt with vintage motorcycle ignition issues, where 5k ohm spark plug caps had the carbon resistor ohm value increase to over 10k ohms. The higher resistance of the plug cap prevented the plug from firing at all. Swap the cap and starts in one kick.

We also deal with, and this is a serious problem, most of the spark plug manufacturers in the industry have stopped making non resistor plugs. Some owners, unaware there is a difference, have installed resistor plugs in ignitions not designed for them. Doing so results in various issues, most often, the ignition does not fire the plug, and in some cases, ruins ignition components.

Thanks for this info ..... How does it relate to our OEM plugs ???? ....Thanks ..... Mike :thumbup:

 

[PMK]

Thanks for this info ..... How does it relate to our OEM plugs ???? ....Thanks ..... Mike :thumbup:

Actually, very easily it relates to oem or aftermarket Spyder spark plugs. Technology of modern high performance spark plugs has far surpassed old school thinking that the appearance of a used spark plug determines the condition of the spark plug. Also hidden wear of a modern spark plug can very easily ruin parts that are far more expensive. Along with the slow degradation of engine efficiency should be avoided by replacing spark plugs with new spark plugs in a time frame or mileage similar to what is recommended by the engine manufacturer, vehicle manufacturer, or possibly the spark plug manufacturer.

Fully understanding the frugality that some owners enjoy regarding their Spyder, I have no issue at all with a person utilizing that opinion. My own actual experience contending with engines / vehicles that utilize COP technology and exotic metal spark plugs has had me replace more COP packs, spending hundreds of dollars to restore performance, efficiency, and reliability.

The wife’s previous Corolla began having coil and plug failures at just over 50k miles on plugs and COPs that are claimed 100k replacement intervals by the manufacturer. The V8 ford 5.4 litre, has now had several sets of spark plugs and 3 sets of 8 new COPs. The Ford was not pushed to extreme mileage before coils began failing. Typically, when one cylinder begins to misfire, other cylinders will fail shortly afterwards.

Learned my lessons years ago regarding COP setups in any vehicle, but as I mentioned, not concerned how others decide to maintain their vehicles.

 

[PMK]

Thanks for this info ..... How does it relate to our OEM plugs ???? ....Thanks ..... Mike :thumbup:

Wanted to add, regarding the Spyder, years ago, the oem spark plugs were replaced with Denso brand high performance spark plugs. Changed out the oem plugs at about mid life of the recommended replacement interval. No failures, just not a fan of NGK if possible. Prefer Densos and those went in.

 

[pegasus1300]

PMK please go into the differences between Denso and NGK. I used them both many years ago and found no real difference. Wondering what I missed.

 

[Cobwebs]

This from an NGK guy.:dontknow:

https://www.spyderlovers.com/forums/showthread.php?115348-Spark-Plug-Change&p=1391772&viewfull=1#post1391772