Harley Davidson Ignition Coil Problems: What You Need To Know

An ignition coil is a component of the spark plug circuit of a Harley Davidson motorcycle that provides electricity to the spark plug. It is responsible for converting the low voltage of a battery into the high voltage needed to spark the gasoline engine.

The spark plug sends high voltage to the combustion chamber, which ignites the fuel mixture and causes the engine to start. An ignition coil is part of the electronic circuit in an engine with an electronic ignition system. It transforms the battery’s voltage to the high voltage required for the spark plug to spark.

Harley davidson ignition coil problems, can be quite troublesome, leading to several bad outcomes. The ignition coil is the primary spark plug of your motorcycle. It ensures a spark from the engine to the exhaust. If you face any issues with your ignition coil, it’d affect the spark output of your engine and lead to bad performance.

Here, we will cover harley davidson ignition coil problems, the symptoms associated with bad coils, and the possible solutions. We will also provide tips on avoiding these issues and keeping your motorcycle running smoothly.

Harley Davidson Ignition Coil Problems

Ignition Coil & Their Types 

An ignition coil is a component of a spark ignition system of an internal combustion engine. It is a coil of wire with a primary coil, which acts as a transformer, and a secondary coil. The primary coil generates a voltage transferred to the secondary coil via an ignition spark gap.

The voltage in the primary coil creates an electric field around the spark gap. This electric field induces eddy currents in the secondary coil, producing voltage amplification that powers the spark plug.

Conventional Ignition Coil

Conventional Ignition Coil

Conventional ignition coils take energy from the battery and convert it to a voltage of 50,000 or more to create a spark that ignites the fuel. Older vehicles with a distributor have a single coil that provides voltage to the distributor.

The original big Twin coil was later replaced by a slimline coil that is more durable and compact, helping to keep the power lead separate from the electrical wire. The ignition coil comprises an iron core and primary and secondary windings connected to the electrical components. It plays a critical role in starting combustion in vehicles and is an essential component of most engines.

Distributor-Less Or Dis Ignition Coil

DIS or Distributor-less ignition coils feature three or-more coils grouped and rely on a device for magnetic triggering to control the speed of the engine and spark timing. To test if a DIS ignition coil is dead, one can use an ignition spark tester or multimeter to test resistance.

DIS ignition coils are usually powered and controlled by an Ignition Module, which can also fail. COP ignition systems have coils that sit directly on top of the spark plug, and the ECM or PCM can regulate spark timing for each cylinder.

Electronic Ignition Coil

Electronic Ignition Coil

Electronic ignition coils are used in automobiles and motorcycles to provide reliable performance and enhanced engine efficiency. An ignition coil is a device that takes low-voltage power from a battery and transforms it into high-voltage power, creating a spark that ignites the car’s fuel mixture. It is an important part of an engine’s ignition system. The coil gets its power from a Harley-Davidson spark plug battery.

Coil-On-Plug Or Cop Ignition Coil

COP ignition coil is an engine component that provides voltage to the spark plug to ignite the fuel in the cylinder. It is a magnetic device typically made up of several turns of wire or a coil of wire wound around a core, with the core acting as an electrical node.

The ignition coil takes energy from the battery and sends it to the spark plug to create the spark needed for combustion. The spark plug usually mounts it, eliminating wires between the coil and plug.

Solutions Of Harley Davidson Ignition Coil Problems

Solutions Of Harley Davidson Ignition Coil Problems

Gasoline-powered vehicles, such as Harley Davidson motorcycles, require an ignition coil to start the engine. The ignition coil is a component that helps create a spark that ignites the fuel in the cylinders and causes the engine to turn over.

When there is a problem with an ignition coil, it can cause various issues, including loss of power and stalling. If you suspect your ignition coil is damaged or malfunctioning, contact a mechanic for help. They can replace or repair your ignition coil and ensure your Harley runs smoothly.

Several problems with Harley Davidson ignition coils can occur, including shorting, cracking, and misfiring. If you notice an issue with your ignition coil. It’s important to take it to a mechanic for inspection and repairs. Here are some common issues and how to fix them:

  • Shorting occurs when the coil shorts out due to faulty connections or manufacturing defects. The resulting spark is weak, leading to misfires and other driving issues. Fixing a shorted coil typically involves replacing the entire unit.
  • Cracking occurs when the plastic indention in the coil fails due to age or use. The crack exposes improperly insulated wire and causes a weak spark. A cracked ignition coil needs replacement.
  • Misfiring is another common issue with Harley Davidson ignition coils due to faulty components or materials used in manufacturing. It can also be caused by dirty or damaged, improperly insulated wires, allowing current to flow freely between them.

How To Avoid Harley Davidson Bad Ignition Coil Problems

How To Avoid Harley Davidson Bad Ignition Coil Problems

Avoid driving with Harley Davidson bad coil symptoms to prevent engine failure or backfire. It is important to check the Harley-Davidson coils regularly for signs of weakness, such as burnt spark plug wires or an arcing coil. Replace the ignition coil if you detect a weak spark. Monitor the engine idle and start-up to ensure the coils are working properly. This will ensure that they don’t become damaged or burned out.

Keep The Spark Plugs In Good Condition

An ignition coil provides the primary current required for fuel combustion. It creates a spark between two electrodes, which in turn creates high-voltage pulses to ignite the fuel mixture in an engine. If the ignition coil is weak or unable to create a spark, it will be unable to start the engine.

In addition, if the ignition coil is not working properly, it might not generate the high-voltage spark signals necessary for combustion. As a result, the engine would not be able to start. You should do regular maintenance to keep the spark plug in good condition and ensure proper performance of the Harley-Davidson ignition coil. This includes replacing the spark plug after each use and keeping them clean and dry.

Keep A Check On The Tires

It is important to inspect the tires of your Harley Davidson at regular intervals to ensure they are in good condition. If either of the tires is worn out, it can affect the functioning of the ignition coil and lead to bad ignition.

It’s also important to replace the tires when they need replacing. You must also properly connect the spark plug and gap in the wire using a multimeter. You should measure the voltage supplied when looking for signs of damage in ignition coils.

Fill The Fuel Tank In Due Time

Fill The Fuel Tank In Due Time

If the motorcycle’s engine fails to start or runs rough, it could indicate a bad ignition coil. This can lead to a misfiring spark plug and poor engine performance. Before attempting to repair the problem, it’s important to diagnose it thoroughly.

First, check the fuel level in the tank regularly to ensure that it doesn’t run out before you can start riding the motorcycle. If your engine consistently fails to start or runs rough, there might be a problem with one of its ignition coils. In this case, replace them with new ones as soon as possible.

Keep Your Motorcycle Clean

Regularly cleaning Harley Davidson is essential to maintain its overall system and function properly. Dirt and grime can accumulate on the motorcycle, leading to issues with the ignition coil. You must, therefore, regularly clean your motorcycle to ensure it operates at its best. You can use a vacuum to remove dust and dirt from engine compartments, wheels, and other areas.

The Harley Bad Coil Symptoms

The Harley Bad Coil Symptoms

Harley ignition coil problems can lead to engine failure or backfire, poor fuel economy, a complete vehicle breakdown, converter damage, and erratic engine noise. Some Harley coil symptoms include poor fuel economy, vehicle stalls, engine failure to start, and misfiring.

Engine misfiring is an easily noticeable coil symptom, indicated by noisy sound, jerking and spitting at high speeds, and a failure to start or idle at stops. Vehicle stalling is another coil symptom that can occur when weak coils send irregular sparks to spark plugs.

Bike Stalling

Failing to start or stall while operating a motorcycle can be a sign of a weak ignition coil in the motorcycle. If the clutch is released too quickly, the back wheel may not have enough speed to match the engine’s RPM resulting in engine stalling. Typically, this problem occurs when the rider accelerates quickly and abruptly releases the clutch, which causes the back wheel to spin without engaging with the engine.

Backfiring Of Engine

Backfiring of the engine is another indication of a weak ignition coil. This symptom occurs when the engine sends excessive sparks to the plug wires and causes an electrical spark that ignites the air/fuel mixture in the cylinder. Dirty or clogged plug wires, incorrect heat range selection, bad cold plugs, and low fuel pressure can exacerbate backfiring.

Reduction In Fuel Economy

Reduction In Fuel Economy

Low fuel economy can also be a sign of ignition coil failure. This is usually due to low voltage and poor spark plug performance caused by weak coils. Low voltage indicates the coil has lost power, and spark plug performance results from misfiring or bad coil quality.

Misfiring Of Engine

Misfiring of the engine can also be caused by weak coils. This problem occurs when spark plug fires are not consistently initiated, which results in low fuel economy and poor performance. Misfiring of the engine often indicates a problem with the spark plugs.

This is due to bad coil quality, inadequate plug wires, or the cylinder’s dirty air/fuel mixture. When misfiring occurs, it produces a loud noise and additional emissions from the engine.

Rough Idling Or Erratic Engine

Rough Idling Or Erratic Engine

If you are experiencing rough idling or erratic engine behavior in your Harley motorcycle, there may be a bad ignition coil causing damage to the engine. A bad ignition coil will lead to engine failure or backfire, producing poor fuel economy and a complete vehicle breakdown.

It is important to check motorcycle engine misfiring as an easy indication that ignition coils are failing. When misfiring, the motorcycle’s engine may jerk and spit, producing unpleasant vibes when moving at high speed. Poor fuel economy, a misfiring engine, and backfiring are all symptoms of bad-coil engine failure.

A bad coil on a Harley Davidson can lead to engine failure causing the vehicle to stall or fail to start. If we don’t address the problem quickly, it may damage other engine parts. Converter damage and other signs of bad coil engine failure are also possible. To replace a faulty ignition coil, disconnect the negative terminal on the battery and remove the coil from the engine bay.


Harley Davidson ignition coil problems, can be quite frustrating. Find possible solutions if you are experiencing issues with your motorcycle’s ignition coil. Additionally, learned about Harley’s bad coil symptoms and how to identify them.

If you are having trouble starting your motorcycle, it is important to check all the spark plug wires and cap them off if they are cracked or damaged. As for fuel system problems, always refuel your motorcycle in time and avoid overfilling it. Keep your motorcycle as clean as possible to prevent any bad coil problems from happening in the first place. Contact experts today if you need help solving your motorcycle ignition coil problems.

Frequently Asked Questions

1.What Are The Symptoms Of A Bad Ignition Coil?

Ans: One of the most common symptoms of a bad ignition coil is misfiring and Check Engine Light. This can be caused by a faulty ignition coil, leading to vehicle stalling, erratic engine with noise, and engine failure or backfire.

2.How Long Do Harley Ignition Coils Last?

Ans: Harley ignition coils typically last at least two years or 24,000 miles. However, some coils have been made to last up to 100,000 miles or more.

3.How Do You Test A Harley Davidson Coil?

Ans: To test a Harley Davidson coil, disconnect the negative terminal from the battery and remove it from the engine bay. If a spark is present at both ends of the coil when connected to an ignition source (light or plug), it is likely in good condition and does not require replacement.

4.How Often Should A Harley Coil Be Replaced?

Ans: You should replace Harley Davidson coils every two years or 24,000 miles, whichever comes first.

5.What Are The Bad Coil Symptoms Of A Harley-Davidson Ignition Coil?

Ans: Most bad coil engine failure symptoms on a Harley-Davidson motorcycle include misfiring, Check Engine Light issues, and other signs of poor engine performance. These problems may escalate into more serious engine damage if not corrected quickly.

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