Why are Harley-Davidsons motorcycles so loud? Surprising things to know

Why are Harley so loud?
Why are Harley so loud?

Motorcycle makes noise as it runs depending upon the company and type it can be a little quiet or louder. That’s where Harley-Davidson motorcycle comes as these motorcycles are generally sound louder than other motorcycles. There has been going a lot of debate about it. Thus in this today’s post, we are going behind the reason Harley-Davidson being loud. 

So, Why are Harley-Davidson motorcycle loud? The only reason Harley-Davidson is loud is that the owners want them to be. People replace the Harley stock exhausts with after-market exhaust or remove the muffler from the exhaust for loudness that exceeds more than 100 decibels when revved up.

Harley-Davidson motorcycles are not louder than any mass-produced motorcycle from the factory. Because all the manufacturers adhere to the decibel level by the government including Harley. 

Some earlier models of the Harley-Davidson motorcycle reached levels upto 90 dB to 100 dB. But today Harley’s motorcycles are manufactured by complying with the EPA regulation. Thus, How do Harley motorcycles become loud?

The Harleys old loud, powerful sounding engine has become a signature for this brand that has now turned into a real threat.

As many riders who buy Harley for the first time remain unsatisfied with the legally regulated stock noise of the engine.

Thus the owner makes Harley louder either by swapping the stock exhaust with the aftermarket one or running with straight pipes without a muffler etc. These things majority make Harley louder otherwise from the factory Harley isn’t that louder.

These things make the Harley sound exceeds upto 100 decibels when revved up. This amount of sound is not safe for the human ear and riders will have to pay a long-term, ear ringing price for making their Harley louder.

Generally, people making their Harley louder gives two reasons. The first reason is that; Riders think loud pipes make them noticeable and cool. 

Secondly, the myth around some riders is that they think loud pipes save lives. It’s a theory that many car drives can’t hear the motorcycle coming their way with windows closes and music running. Thus, riders made their Harley exhaust loud enough that car drives notice one coming.

There is also some non-Harley riders than swapping their exhaust pipes just to sound like Harley because they also believe on other two points.

While the truth is the opposite; loud exhaust pipes annoy people around you and create a bad image about motorcycle riders. And, riding with loud exhaust doesn’t save your life; riding with proper gear and awareness saves one.

Thus, stop doing idiotic things to make your motorcycle louder either it is Harley or any other, and be responsible towards people and the environment. Because a loud pipe produces a noise level of 95 decibels to 100 decibels. According to cdc.gov, Even noise above 70 dB may start to damage your ear if hear for a prolonged time. Apart from this, a loud noise above 120 dB can immediately harm your ears.

Noise level Comparision for Harley-Davidson motorcycle (Audio included)

Harley-Davidson motorcycle makes the type of sound because of the V-twin engine design. People loved its sound, it becomes a signature. 

In order to fully grasp the sound level specified, you are gonna need a comparison value. So, here it is.

A soft whisper is about 30 dB, normal human conversations about 60 dB. Generally, a motorcycle engine running lies between 80 dB to 95 dB and louder (if uses aftermarket exhaust).

Here is the audio of a human whisper.

This is the sound of a normal motorcycle.

Here is the sound of Harley-Davidson motorcycle. (modified exhaust)

Harley-Davidson motorcycle exhaust can emit noise as high as 80 decibels, it can vary a little high or low depending on the model. If you are thinking that there is only the difference of 20 decibels between the noise level of human conversation and Harley engine sound. So, how can Harley be louder?

Let me tell you one more thing if you are thinking that there is not much difference between 60decibels and 80 decibels then you are wrong. The decibel system is a logarithmic function, thus an increase in 10 decibels means that the sound is ten times louder. (10x)

Why does Harley-Davidson motorcycles sound like they do?

Harley-Davidson engines are V-twin engines that come with a 45-degree angle between the cylinders. The 45-degree angle allows a large, high-torque engine in a relatively small space. This causes the cylinders to fire at uneven time intervals and produce the choppy “potato-potato” sound.

Here is the Harley-Davidson motorcycle potato-potato sound.

Harley-Davidson potato sound

There is no denying that the Harley-Davidson motorcycle sound is distinctive from any other motorcycle. The reason Harley sounds like they do is the way its engine is designed.

Harley-Davidson engine comes with V-twin with a 45-degree angle between the cylinders and a single crankshaft pin that hold the two pistons. This is the engine that produces the famous potato-potato sound. The potato-potato sound is so tied to the brand that Harley at one time even applied for a trademark on it.

Now, you guys may be thinking Why does the V-twin engine make potato sound? Let’s get into it.

Before getting into the reason for Harley making potato sound. Let’s understand, “How motorcycle engine produces noise”?

“Motorcycle engine sound is produced by the compressed gases exciting the cylinders through the exhaust valves and then through the exhaust system where they are either muffled or amplified depending on your exhaust system and muffler setup.”

So, a Harley engine has two pistons connect with one pin to the crankshaft. Because of this engine design, combined with the V arrangement of the cylinders, the pistons cannot fire at even intervals. The Harley engine works differently, instead of firing one piston every 360 degrees, the Harley engine goes like this:-

  • A piston fires.
  • The next piston fires at 315 degrees.
  • There is a 405-degree gap.
  • A piston fires.
  • The next piston fires at 315 degrees.
  • There is a 405-degree gap.

And the cycle continues. This produces the pop-pop or says famous potato sound of the Harley-Davidson motorcycle.


Every manufacturer adheres to EPA (Environmental Protection Agency) regulation for street-level noise including Harley.   

Thus Harley-Davidson motorcycles are not louder, it has a different sound than other motorcycles because of the way it’s engine made. Having different sounds doesn’t make it louder.

Harley-Davidson motorcycles are as quiet as any other mass produces motorcycle in the market. It’s the owner of the Harley-Davidson that makes them loud by replacing the motorcycle exhaust or muffler (running with a straight pipe). These things are illegal in most countries, thus don’t make your motorcycle unnecessarily louder, it affects people and the environment also. 


Can I make my Harley quieter?

You can make your Harley-Davidson motorcycle quieter by running it with stock exhaust and by using a dB killer. dB killer helps to kill the higher frequency coming from the exhaust. Apart from this, make sure to avoid any after-market exhaust that increases the loudness of your motorcycle. As any motorcycle coming from the factory can’t exceed 84 decibels (dB).

Sources that helped me to write this article:-


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