Riguarda la candela, quelli piccoli, creature robuste che si avvitano nel tuo motore e forniscono i pugni dell'elettricità per accendere la tua miscela aria-carburante per le perfette prestazioni del motore a combustione e il suono associato alla tua Harley.
Fondamentalmente, le candele sono dispositivi semplici, but highly accurate and made of materials that must withstand extreme forces of heat, vibration, and electricity. They have to be strong enough to withstand years of abuse, and elastic enough to withstand years of constant vibration and jarring.
A good spark plug will be built for endurance and performance and have high-grade metal tips to withstand constant sparking. The materials must be constructed with compatible coefficients of expansion so that the heat will not cause them to crack or break apart.
As you can now ascertain, that solid little plug is much more than it seems.
Maintaining a plug is imperative, and there are signs of wear and tear that will help you understand what the problem is and how to fix it. In the following list, I present to you the major issues associated with spark plugs. When you encounter such an issue, you have to consider cleaning or changing your plug.
Replacing spark plugs before their expected expiration is the best way to assure a safe and healthy ride for you and your engine. Now, let’s take a look a the list that was nicely made up by the people at Briskusa.com, they also supplied four photos to show the appearance of the plug, take into account these are all plugs that have been in use for a year or over.
One of the keys to success is making sure the gap is correct, and this is done by checking it with a standard spark plug gap tool.
When you need to expand or reduce the gap, remember that the force you need to exert must only be on the spark plug ground electrode strap. Never ever apply any force on the spark plug center electrode or center electrode ceramic insulator.
Another rule is that you should never change the gap more than three times in the plugs lifetime, and never more than .008″ in either direction. Another rule to remember is that you never exceed .055″ beyond the manufacturer’s tolerance unless this is already pre-set by the manufacturer.
cross reference chart – metric to standard (mm to the inch)
| mm | 0.4 | 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | 1.0 | 1.4 | 1.5 | 1.6 | 1.7 |
| inch | .016″ | .020″ | .024″ | .028″ | .032″ | .035″ | .039″ | .055″ | .059″ | .063″ | .067″ |
List of Top-Rated Spark Plugs for Harley Davidson Comparison Table:
| Product Image | Product Name | Year | Model | More Information |
|---|---|---|---|---|
 | NGK Iridium IX DCPR7EIX Spark Plugs for 1999-2016 Harley Davidson Twin Cam (Pair) | 1999-2016 | Twin Cam (Pair) | More Information |
 | ACDelco 41-993 Professional Iridium Spark Plug (Pack of 4) | 1995 | Twin Cam/Sportster | More Information |
 | E3 Spark Plug E3.36 Powersports Spark Plug, Pack of 1 | 2014-2016 | Street Glide Special FLHXS | More Information |
 | Champion Spark Plug RA8HC for Harley-Davidson Street Glide Special FLHXS 2014-2016 | 2014-2016 | Street Glide Special FLHXS | More Information |
 | DENSO # 3297 Iridium LONG LIFE Spark Plugs – SK20R11-4 PCS NEW | 2007 | Twin Cam/Sportster | More Information |
The Best Spark Plugs for Harley Davidson Reviews & Buyer’s Guide:
Navigation
1. NGK Iridium IX DCPR7EIX Spark Plugs for 1999-2016 Harley Davidson Twin Cam (Pair)
The NGK plugs are made from a fine wire center electrode that comes with a Copper Core and an Iridium Alloy tip. The nickel electrodes have an Extremely High Melting Point and come with a Trivalent Metal Plating sealed in a Pure Alumina Silicate Ceramic Insulator with Corrugated Ribs.
These spark plugs provide extreme thermal resistant properties, excellent electrical insulation characteristics and are designed to withstand a lot of vibration and knocking.
The threads are 12mm at a 1.25mm pitch, and the seat is a gasket type. Thus, the model comes with a 5K Ohm resistor and has a reach of 19mm ¾”, the gap is .031″ (0.8mm). The terminal uses a removable nut, and the overall height is rated as JIS.
Recommendations
This is a generic make that fits many applications, even so, check before you install any spark plug, and make sure the gap is to manufacturer requirements before sealing the plug-in place.
2. ACDelco 41-993 Professional Iridium Spark Plug (Pack of 4)
ACDelco is a company that boasts many years of experience in producing high-quality performance general motors original equipment parts. The ACDelco iridium spark plug is engineered to offer enhanced engine idle stability and extra smoother performance. It features iridium fine-wire electrodes that ensure improved cold starting and quicker acceleration. Again, iridium ensures improved ignition of the fuel and burning off carbon deposits formed on the tip of the plug, thus improving fuel economy.
Recommendations
ACDelco iridium spark plug is the ideal choice for performance machines such as Harley-Davidson thanks to smoother performance. What’s more, it comes with a one-piece suppressor seal that inhibits any radio frequency that can affect vehicle electronics.
3. E3 Spark Plug E3.36 Powersports Spark Plug, Pack of 1
The E3.36 comes with 12mm, ¾” reach the plug and uses a gasket seat design. This model is used in the more modern Harley Davidson bikes, and as such, it is engineered specifically for these applications.
This model comes with the patented DiamondFIRE ground electrode, this electrode uses to legs to attach to the shell, and this optimizes heat transfer, as well as provide additional absorption of intense vibration.
This model comes with a 5K Ohm resistor and has a 5/8 hex. The electrode is a copper core nickel model, and the gap is rigid and preset, so you cannot (must not) adjust it.
Recommendations
This is a bespoke spark plug for very specific applications, it can only be used on 2014-2016 Street Glide Special FLHXS models, and is the best spark plug for them too.
4. Champion Spark Plug RA8HC for Harley-Davidson Street Glide Special FLHXS 2014-2016
Champion Motors is a leader in spark plug innovation and development. They are the original company that created the first commercial spark plug way back over a century ago. This model is their bespoke spark plug model for all Harley-Davidson Street Glide Special FLHXS 2014-2016 models.
This is a copper core spark plug that uses nickel alloy electrodes E thermal bonding, to create a wider insulator base, with a long insulator nose. The nut is non-removable.
This spark plug comes with an 8-heat range rating and has a standard 12mm thread with a 5K Ohm resistor.
Recommendations
If you own a Harley-Davidson Street Glide Special FLHXS 2014-2016 model bike than this is the plug for you, and you really shouldn’t use any other model. This is a proven and great spark plug at a great price too.
5. DENSO # 3297 Iridium LONG LIFE Spark Plugs – SK20R11-4 PCS NEW
DENSO Iridium spark plug is the first to use iridium on spark plugs and it’s now becoming the most popular device for modern high-tech engines. This company has employed the 360-degree laser-welding process to create a performance spark plug that is durable. Featuring state of the art technology, this device is engineered to offer unmatched functionality, reliability, and fitment.
Recommendations
This is one of the best and long-lasting spark plug in the market, thanks to its iridium electrodes. With Iridium electrodes, the DENSO performance spark plug offers improved acceleration, enhanced fuel economy, and prevents engine misfires.
