Spark Plug Types? - Page 4 - KTM Duke 390 Forum
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post #31 of 49 Old 09-07-2016, 03:06 AM
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Just received 1 lot yesterday containing 4 spark plugs. Ordered it from aliexpress.com LKAR8AI-9 Laser Iridium

Will fit it soon enough. hope it works out well.
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post #32 of 49 Old 09-07-2016, 10:31 AM
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Rideontt, Thanks for posting this very helpful video, which clearly explains the - significant - differences in heat conductivity of the various metals used in spark plugs. I actually found this video last year when I was shopping for new plugs for my Duke. Based on the Duke's propensity to run hot, I selected the NGK copper core plug (LKAR8A-9) because of its much better heat conduction as opposed to the Irridium version (LKAR8AI-9) of the same plug. The Irridium has the advantage of exceptionally long service life; but its disadvantage is low thermal conductivity, which can make the engine run even hotter and could lead to preignition/detonation.
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Cheers, Will

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post #33 of 49 Old 09-07-2016, 01:33 PM
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@Diploman.

I will fit the same. Try it out....
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post #34 of 49 Old 09-07-2016, 03:12 PM
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When I ordered the NGK copper-core plugs for my Duke, I was surprised when they arrived in KTM packaging. This I took to mean that the copper-core plug, rather than the Irridium version, is the standard plug KTM intends for use with the 390 engine.
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Cheers, Will

"If you don't know where you're going, you might wind up somewhere else."
--Yogi Berra

2015 390 Duke
1980 Moto Guzzi V50 II cafe racer
1984 Moto Guzzi SP 1000

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post #35 of 49 Old 09-07-2016, 06:14 PM
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As Partha Saika 2 has an iridium plug ready to fit, then I'll just point out that it is my understanding that the heat dissipation for both NGK plugs will be the same as I believe this is directly related to the heat range of each plug (8) which as mentioned earlier in this thread is also colder than the heat range of the stock Bosch item.

So based on my understanding, either of the NGK plugs will run cooler than the stock Bosch item.

I realise that iridium tips are relatively poor heat conductors but presumably this is compensated for elsewhere in the plug design to arrive at the same heat range as the non iridium tipped NGK plug.

Page 3 of THIS guide is a good reference on the topic of heat range / heat dissipation.

THIS other guide from NGK explains about their use of copper cores.

As I've just fitted a LKAR8AI-9 then naturally I also wanted to reassure myself it wasn't a rash decision

Less is more - You can only use 150hp .001% of the time, but you can use 150kg 100% of the time ...........


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post #36 of 49 Old 09-10-2016, 08:14 AM
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Fitted the laser iridium plug NGK LKAR8AI-9 6706. Changed engine oil 300v 15w50. Changed the radiator fan with kinetic tiagene.
The iridium is really feeling punchier to ride over the Bosche VR5NE. The fan too kicks in as it used to earlier. The old fan has become a little harder rotate.
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post #37 of 49 Old 02-22-2017, 11:43 PM
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An interesting read from the NGK site:
Heat Range

The term Heat Range refers to the speed with which a plug can transfer heat from the combustion chamber to the engine head. Whether the plug is to be installed in a boat, lawnmower or race car, it has been found the optimum combustion chamber temperature for gasoline engines is between 500C–850C. Within that range it is cool enough to avoid pre-ignition and plug tip overheating (which can cause engine damage), while still hot enough to burn off combustion deposits that cause fouling.

The spark plug design determines its ability to remove heat from the combustion chamber. The primary method used to do this is by altering the internal length of the core nose. In addition, the alloy compositions in the electrodes can be changed. This means you may not be able to visually tell a difference between heat ranges.

- When a spark plug is referred to as a “cold plug”, it is one that transfers heat rapidly from the firing tip into the engine head, keeping the firing tip cooler.

- A “hot plug” has a much slower rate of heat transfer, which keeps the firing tip hotter.

An unaltered engine will run within the optimum operating range straight from the manufacturer, but if you make modifications such as adding a turbo or supercharger, increasing compression, timing changes, use of alternate fuels, or sustained use of nitrous oxide, these can alter the plug tip temperature, necessitating a colder plug.

A good rule of thumb: use one heat range colder for every 75–100hp added.

In identical spark plug types, the difference from one full heat range to the next is the ability to remove 70C to 100C from the combustion chamber.

The heat range numbering system used by spark plug manufacturers is not universal.

For example, a 10 heat range in Champion is not the same as a 10 heat range in NGK nor the same in Autolite.

Some manufacturers numbering systems are opposite the other - for Champion, Autolite and Bosch, the higher the number, the hotter the plug. For NGK, Denso and Pulstar, the higher the number, the colder the plug.

It is not recommended that you make spark plug changes at the same time as another engine modification, such as injection, carburetion or timing changes. Performing too many modifications or tune-ups at once will lead to misleading and inaccurate conclusions if any issues occur (an exception would be when the alternate plugs came as part of a single pre-calibrated upgrade kit).

When making spark plug heat range changes, it is better to err on the side of too cold a plug. Running too cold a plug can only cause it to foul out, whereas running too hot a plug can cause severe engine damage.

As the illustrations did not transfer with copy/paste go to https://www.ngk.com/product.aspx?zpid=9876 click on "specs" then click on "heat range" under "Specifications"

Enjoy.
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post #38 of 49 Old 02-24-2017, 12:47 AM
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Hi Partha Saikia 2,
Can you tell me more on the cooler fan you installed from kinetic tiagene?
As, where I live it seems virtually impossible to get the SPAL Italian designed replacement all of North America is talking about.
Might give this a go.
Thanks.
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post #39 of 49 Old 02-24-2017, 04:43 PM
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there are some strange brisk spark plugs

i will give them a try. the item fits both 200 and 390 engines.

some reviews for drz owners said that they have seen some better performance, mostly at low rpms.

it is believed also that there are better from iridium
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post #40 of 49 Old 03-15-2017, 06:07 PM
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Quote:
Originally Posted by Partha Saikia 2 View Post
Fitted the laser iridium plug NGK LKAR8AI-9 6706. Changed engine oil 300v 15w50. Changed the radiator fan with kinetic tiagene.
The iridium is really feeling punchier to ride over the Bosche VR5NE. The fan too kicks in as it used to earlier. The old fan has become a little harder rotate.
would like to know more about "Kinetic Tiagene" my stock fan is a ***** ...
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