Harley Davidson No Spark Troubleshooting

One of the most annoying Harley Davidson problems is a no-spark scenario. However, there is no reason why you cannot get it running once more. In this article, we’ll teach you how to troubleshoot that peculiar issue and possible solutions to problems your motorbike might have. 

Conditions Necessary To Produce The Spark

Your ignition coil needs to meet a few requirements to generate the high-spark voltage. The likelihood that they will damage the ignition coil if they are not in good condition is substantial.


The ignition coils have two spots: “start” and “run.” The switch starts the starting motor in the “start” mode. The engine starts while the coil is routed with full battery power. 

The switch turns to the “run” position when it starts. Then, you should thoroughly examine the battery. There may be a problem if the circuit’s and the ignition coil’s voltage supply are not constant or reliable.


The coils experience voltage if no outside signals are provided as input. This won’t cause any secondary sparks. A disruption in the circuit that results in a high voltage in the coil windings results from a switch or signaling device. Each spark also coincides with this voltage change. 

Unlike traditional ignition systems, circuit design systems can detect the requirement for a spark. As a result, it produces a crankshaft position sensor or hall-effect switch. Check the ignition system’s parts to determine whether your bike has a defective coil.


In most cases, ignition coils generate a stable secondary voltage. It will go to the distributor cap through the hollow hose. Though if it passes through a large gap or a layer of deep rust, the coil won’t fire. 

For the circuit to successfully supply a voltage, ensure the secondary spark conductors are hand in hand with solid connections and the appropriate shielding.

Open Circuits

Any time a sensitive part is harmed or broken, an open circuit results, which can be hazardous. Moreover, you should use an Ohmmeter to check the coil windings’ continuity. There will be enough resistance from broken connections for an open circuit. Additionally, the condition of the battery and the engine are crucial.

How Do You Know If Your Harley Coil Has Malfunctioned

Here is how you can find out if your coil has gone wrong:

  • Your motorcycle uses more petrol than average or runs out faster than usual.
  • Whether your engine is rich or lean, it is rich when there is more gasoline than air; otherwise, it is lean.
  • If the ignition coil is faulty, your bike will stop while the engine runs.
  • When the engine doesn’t start, it’s one of the most apparent symptoms of damaging the ignition coil.
  • The bike jerks due to faulty ignition coils. Even when you accelerate, the engine won’t increase its power; instead, it will emit loud sounds.
  • After ignition, if you hear loud sputtering or noises akin to coughing, a faulty ignition coil may be to blame.

How Can You Troubleshoot and Find A No-Spark Issue?

Before attempting to fix a problem, it’s usually a good idea to conduct a thorough diagnosis to ensure you know exactly what’s wrong. You should check the gasoline, spark, or compression if the engine appears to crank correctly but does not ignite.

Use the following approach to determine if there is a spark or not:

  • The air input tube must be separated from the throttle body. To start, release the throttle top. Put some aerosol starter spray into the engine. 
  • After that, start the bike.
  • The motor has a spark issue if it won’t start.

Resolving The No-Spark Issue Of Harley Davidson

It would help if you first detached a spark plug and then reconnected the plug wire. Ensure the insulator is well in line with the metal structure of the pin. We’re referring to the ceramic insulator if you’re unsure which part is the insulator. 

We highly recommend bringing a friend for the next step. Ask them to engage the ignition or start the engine. You keep a close eye on the surface of the electrode of the connection.

You can proceed at this point if you observe a blue or yellow spark bridge filling the gap. It signifies you have had enough fire to start the cylinder’s gasoline.

Switch on your bike if you do not notice any spark. It is possible that your vehicle’s ignition switch will malfunction under certain conditions. 

In addition, your Harley’s security system could not receive enough power if fitted. And that might prevent the bike from starting.

Find the coil-powered button now. Inspect if the current flows from the coil and hits the spark plug cap using a voltmeter or lamp tester. 

As each engine starts, you must receive an on/off reading for each engine revolution. If you do, you must use the previously mentioned procedures to replace the damaged spark plug with a new one. You must use a wire or cap instead of the spark plug if it cannot accept AC power.

If your motorcycle is a bit dated, check the current flow at the engine and condenser terminals from both sides. 

Ensure the pieces are in good shape by closely inspecting them. You can solve problems by changing parts if they are ancient or the ignition coil seems feeble.


Q1. What are the different types of plug gap configurations?

The ground electrode splays a little beyond the threading height, and the central wire tip is often nearly even with the border of the threads.

In an expanded tip plug, the earth electrode is proportionately farther out, and the insulator surrounding the center wire and the center wire protrudes over the threads’ level. The combustion chamber can be more evenly heated by projecting the tip there.

A suitable wire plug’s central wire has a smaller footprint than a conventional plug. The ground electrode is joined to the interior of the threaded piece of a retraction gap plug, which also contains the center wire and the electrode.

The conventional ground electrode and center wire layout is not used with the surface gap plug. These plugs differ in more ways than appearance; they have highly distinct performance traits and are made for specific engine, fuel, and ignition systems.

Because of this, it is essential to avoid randomly experimenting with spark plug replacement. The best approach to maximize performance, avert any engine damage, and safeguard your warranty is to use the spark plug types recommended by your bike’s manufacturer.

Q2. Are there different heat ranges for spark plugs?

It’s critical to stay within the temperature range recommended for your engine. Nevertheless, a motorcycle’s maker may provide several spark plug heat range possibilities for certain operating or climatic circumstances. 

Before switching to a heat range different from what is prescribed, consult your owner’s handbook and the dealer’s.

Although spark plug replacement can improve performance, it is important to follow the manufacturer’s guidelines. To optimize engine power without reducing engine life, it is a good idea to contact a speed modification specialist if you have engine modifications.

One may visually determine the thermal range by measuring the insulator’s circumference and length. Generally, a longer, thinner insulator denotes a hotter heat range plug, whereas a smaller or thicker insulator structure denotes a more excellent heat range.

Companies may provide brand cross-reference charts to help consumers choose spark plugs and additional in-depth data on the heat ranges of their items. 

Numbers convey heat ranges, with lower values (2-6) representing hotter plugs and higher ones (7-11) meaning colder plugs.

Q3. When should I replace my Harley Davidson Spark Plugs?

Since they fire the gasoline and air combination that propels your motorbike down the road, spark plugs play a crucial role in how your motorcycle engine functions.

You will eventually need to replace Harley spark plugs along with the tires and oil. Although the lifespan of a motorcycle spark plug varies depending on the model, it typically lasts between 15,000 and 20,000 kilometers. 

Now that range is considerable and based on the motorbike you ride, it may be higher or lower, so verify the manufacturer’s standards for your particular longevity.

Begin by determining potential problems that a failing spark plug might cause if you are unsure how many miles you have driven with your present pin.

Q4. What’s the electrode gap in a Harley Davidson spark plug?

A powerful ignition spark depends on the ground electrode and a center electrode having the proper spacing between them. 

The engine might misfire, or your fuel economy can increase if the gap is incorrect. The spark plug won’t light if the ground electrode is bent relative to the center electrode, such as if you threw the spark plug unintentionally on the floor. 

Poor burning would result from a too-tiny gap, and excessive gap size would need more ignition energy than the ignition system can produce.


Harley Davidson bikes are so well built that their parts are also expensive. You can get some OEM spark plugs for cheap, but we suggest you take no chances and go with the original ones.