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Best Spark Plugs for a Harley-Davidson

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A spark plug is a device that delivers electric current from the ignition to the combustion chamber of an engine to ignite the compressed mixture of air and fuel. 

All motorcycles, including those from the Harley-Davidson company, require a suitable spark plug for optimum starting as well as engine performance.

Below are the best spark plugs for Harley-Davidson motorcycles.

Best Spark Plugs for a Harley-Davidson

1. NGK Iridium IX Spark Plug

4 New NGK IRIDIUM IX Spark Plug LTR6IX-11 # 6509
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As of: 2020/08/28 7:51 pm - Details
4 New NGK IRIDIUM IX Spark Plug LTR6IX-11 # 6509 *
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These are twin cam spark plugs, and when used, they give a gain of up to 3 HP. The NGK Iridium IX spark plug has an electrode of 25% smaller than that of platinum. It is a quarter size when compared to a conventional nickel electrode. It has an ultra-small diameter of the electrode at the center, which reduces the requirement of the voltage and extends the life of the ignition system. 

With the new metal shell plating, there has been an enhancement of anticorrosion qualities. Still, these products come pre-gapped. This plug is recommended as one of the best spark plugs for Harley Davidson motorbikes.

2. E3 Spark Plugs

E3.54 E3 Premium Automotive Spark Plugs (8 PACK) - 100K miles / 5 years Warranty
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As of: 2020/08/28 7:51 pm - Details
E3.54 E3 Premium Automotive Spark Plugs (8 PACK) - 100K miles / 5 years Warranty... *
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Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on https://www.amazon.com/ at the time of purchase will apply to the purchase of this product.

These types of plugs are efficient and have smooth acceleration. The E3 Spark Plug is a branded ground electrode module that provides more efficient burning fuel of your motorbike or vehicle, thereby having more pressure inside the cylinder. 

The Diamond electrode extends this spark into the combustion chamber, which brings it closer to the robust fuel/air mixture. 

The initial ignition wave leaves the spark zone at supersonic speed, and the lifted edge provides a chimney impact to allow the same procedure to occur more quickly in the next round. Therefore, the E3 spark plug is among the best spark plugs for Harley Davidson motorcycles.

3. Screamin’ Eagle Performance Spark Plug

Screamin Eagle spark plug

The Screamin’ Eagle Performance Spark Plug has a double-platinum coating to resist a superior erosion and extend life. It has a ‘V’ trimmed ground electrode that reduces the chances of covering the from the side of the flame. This promotes flame propagation. 

The fine wire at the center of the electrode facilitates the startups as well as the ability to ignite. It is designed with some original equipment that suppresses noise and inhibits electrical interference with other devices such as radios. 

Also, it is featured with Ribbed Core Technology, which is resistant to fouling. It works excellently in application races, which require rich fuel/air. 

This design of the spark plug is a unique style and is sold in pairs. It is appropriate for the modified engines inclusive of the high flow air cleaner, performance carburetors, exhaust systems, camshafts as well as the ignition systems together with the compression ratios of the stock.

4. Harley Davidson Original Equipment Spark Plug

HD spark plug

Harley Davidson original equipment spark plugs are sold each separately. They are entitled to a one-year limited warranty. However, it is out of stock at the time of writing. The original equipment Harley Davidson spark plug is very popular, and they have a more extended life service.

5. Gold Spark Plug

Briggs & Stratton Spark Plug Platinum For OHV Engines 5066K
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As of: 2020/08/28 7:51 pm - Details
Briggs & Stratton Spark Plug Platinum For OHV Engines 5066K *
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The Gold Spark Plug is associated with having a unique thread and a shell coating that ensures that there is an easy and quick means of removing aluminum heads, and it also resists corrosion. It has gold-palladium, which extends life and strengthens it to resist corrosion. 

The tapered tip gives a good spark exposure to the fuel/air mixture and also permits a smooth flow through the gap zone for a maximum ignition. The small diameter at the center of the electrode wire plus the insulator tip improves the fouling resistance. 

The ground electrode with copper core runs cooler to make it last longer. It also has threads that do not seize to coat.

Harley Davidson Spark Plugs FAQs2017 Harley-Davidson Touring models get the 107 Milwaukee Eight engine Road King air-cooled

How often should you change spark plugs on a Harley Davidson?

Spark plugs are some of the things that you rarely think about when riding your motorbike. They do not appear in your standard checklist, such as turn signals and tires, among others. However, you should not ignore spark plugs completely because they need replacement at some points for the motorcycle to continue giving you the services you require appropriately. 

Proper installation and maintenance of spark plugs is key for enjoying the top performance of the bike. The big question is, how often should you replace the spark plug of your motor vehicle?

In modern motorcycles, spark plugs should be replaced after every 15,000 to 16,000 miles of riding your motorbike. However, if your bike is sputtering, running rough, or even losing power, just think about inspecting and replacing the spark plug.

If you are buying a second-hand motorcycle, you should ask the seller the last time they changed the spark plug. If the previous owner does not remember or isn’t sure, consider replacing them immediately to ensure your safety.

It is worth noting that when replacing the spark plug, you need to check its compatibility. Make sure that your spark plug is well compatible with the model and the make of your motorbike and also the type of the engine. Also, you should consider its compatibility with your fuel.

Another consideration is the functionality of the spark plug and its improvement in engine performance with regard to power efficiency, ignition time and fuel economy.

Do iridium spark plugs increase performance?

Yes, iridium spark plugs increase performance in that they produce enough sparks to ignite the fuel-air mixture in the ignition system. Using a correctly gapped spark plug and a new one inhibits early combustion or even skipped firing, which may end up damaging the engine.

Iridium is not among the great conductors of electricity, but that does not limit it in performing as a spark plug. In fact, iridium outdoes the copper version and has a service life of around 60,000 miles.

Which is a better spark plug material, iridium or platinum?

There are several things to consider when it comes to determining which is a better spark plug, iridium or platinum. Some of these factors are durability, efficiency, and reliability, among others.

For instance, platinum may be harder than copper, but iridium is the hardest of them all. Therefore, an iridium spark plug can outdo a platinum spark plug.

Again, in terms of performance, iridium performs better than platinum. Still, iridium has a longer lifespan and is more durable than platinum. 

The only downside of iridium is that it is expensive and difficult to find in the market, but once you find it, be sure of working with it for a long time without the demand for any replacement. Therefore, iridium is much better than platinum.

What is the benefit of iridium spark plugs?

Iridium spark plugs have the following benefits:

1. Improve Acceleration

Do you have a problem with accelerating your motorcycle? If so, then switch to iridium spark plugs because this will improve your acceleration. There is a fast response to strangulate operation, and you will automatically feel that difference compared to other plugs.

2. More Engine Power

Every driver wants to be able to climb hills comfortably. With an iridium spark plug, climbing any hill is not a problem. It helps in improving engine performance in regard to power. That extra power is apparent in different situations such as climbing hilly places, and this contributes to giving you a comfortable touring and as well as driving experience.

3. Improve Starting and Combustion Characteristics

Iridium spark plugs have an ultra-fine center electrode that ensures fast combustion and also improves the starting characteristics of the engine. There is little dispersion and more so at the position of the spark, which makes the motorcycle stable even at low speeds.

4. Fuel Economy

Would you like to cut your fuel expenses? Iridium spark plugs have a better fuel economy. These plugs ensure there is a proper ignition, and this gives gasoline time to be burnt efficiently. These plugs do not only give you an economic benefit only, but they also provide environmental benefits.

  1. I’ve been running Champions in every Harley I’ve ever owned Wl’s sportster, Evo, knuckle, shovel, pan and twincam, revetech and S&S, and a Gilroy Indian. Champion has given me reliability. On multiple occasions I have had people bring bikes to the shop thinking they had a major problem. Pull out the NGK’s that are at the end of their short lives, throw in some Champions and off they go. I know of other shops that did the same thing but charged the customer for full electrical diagnosis, to the time of $300

  2. I bought 2 for my 2012 HD ultra. The normal gap for my bike is .040. These plugs come in the box around .030. Do I need to regap these plugs?

  3. Sorry mate. I find the article nothing but puff. And right in it we find those two favourite words of marketing reptiles “up to” which are meaningless tripe. Gains “up to” mean what? The dyno testing I carried out a few years ago with several different brands of spark plugs showed no measurable difference on the dyno at all. None. Nada. Zilch. The dyno of course does not measure longevity are the rate of performance loss of time but none of the parameters it does measure showed any difference.

  4. A few months ago I thought I would try an Iridium spark plug in my bike. It is a 2003 BMW F650CS single cylinder sports bike, a reasonably obscure model. Has 50,000 k’s on it. Had the bike for 15 years.

    This and the first years model are renown for a flat spot and lack of trackability when pulling away from low revs in 2nd and 3rd. It does not like city stop start traffic. The next two years models have twin spark plugs to overcome this, an upgrade I have contemplated if ever I had to pull the head off.

    The Iridium spark plug has virtually eliminated this problem. A huge difference. Also the bike starts quicker, first turn over most times. Previously it would be about the third turn over when cold.

    I cannot comment on any increase in power or improved fuel consumption, the bike goes fine and improvements would be too marginal to quantify.

    So for $23 delivered the Iridium spark plug was well worth it. It was impossible to find in local bike shops and hard to find online. Funny thing is my iridum spark plug part number is only listed for a Ferrari. It would have been amusing rocking up to Ferrari spare parts to see price and availability for one spark plug please.

  5. What a load of shite. If this was the case every race team would run iridium plugs and tbere would be dyno runs in the thousands to back up the claim. Who paid for this ‘article’… HD of course!

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