Why Are Harleys Always So loud? (Explained!)

People criticize Harleys for many things; major talking points include their average performance, enormous weight, and rebellious image.

However, the biggest problem everyone seems to have with Harley-Davidson motorcycles is their excessive loudness.

Why do Harley-Davidson motorcycles operate at deafening sound levels?

Let’s find out!

Why are Harleys so loud?

Many Harleys are loud because the owners want them that way. New Harleys from the factory don’t exceed the 80db limit stipulated in the U.S. EPA Code. It is Harley owners who make several aftermarket modifications on their bikes to turn up the volume.

Such changes include removing bike mufflers, replacing stock exhaust pipes with straighter aftermarket variants, or replacing the entire exhaust system.

Are Harleys Engineered To Be Extra Noisy?

Undoubtedly, Harley-Davidson motorcycles are some of the loudest in the market.

The sound level of the average Harley is around 70 decibels to 80 decibels. A car produces about 50 to 60 decibels of sound. This makes a Harley louder than the average car and most motorcycles.

But does this mean Harley-Davidson deliberately builds its bikes to be extra-noisy? No, it doesn’t.

Factory-produced Harleys are loud, yes, but not louder than is permitted under the law. Federal law stipulates an 80-decibel limit for all motorcycles. Harley-Davidson has to comply with this law, and every bike coming out of an H-D factory is not louder than 80db.

Those ultra-noisy Harleys you hear exist because their owners deliberately increased their sound level, not because Harley-Davidson made them like that. Some people enhance the sound level of their Harleys from the stock 80db to over 100db [we’ve seen cases of 110db]. 

Harley-Davidson gets blamed for the problem because it often ignores attempts by owners to make their bikes louder. It has even subtly encouraged the practice in the past. H-D knows that most of those who buy its bikes will eventually modify them. To take advantage of this, Harley dealerships often offer aftermarket modification packages to customers when selling the bikes.

Loud pipes are a part of the Harley image, and most people buy Harleys intending to make them louder.

However, Harley-Davidson is making efforts to eradicate the practice of owners modifying the exhausts on their bikes. For example, the H-D manufacturer warranty will not cover non-street legal parts and accessories or any problems caused by installing those parts. This includes exhaust systems.

Check out our article that talks about Do Harleys Depreciate or Increase in Value?

Why Do Harley Owners Like Louder Bikes?

People like riding loud Harleys for various reasons. Some like loud bikes because they make them look cool and enforce the macho image they try to project.

Others claim to prefer louder exhausts because they help improve motorcycle performance. Mechanics have, however, debunked this belief. Louder exhaust pipes do not increase performance and may even reduce the performance of the said motorcycles.

The “Loud Pipes Saves Lives” theory is another primary reason owners modify their bikes for increased sound levels. According to the theory’s proponents, louder pipes make you more noticeable on the road. Therefore, car drivers will know of your presence and avoid hitting you.

The problem with this theory is that it ignores the fundamental laws of physics. Sound from exhaust pipes travels backward, meaning drivers won’t hear until you’re beside or ahead of them.

Therefore, louder exhausts will not prevent a driver from pulling out ahead of you without warning or T-boning you at a junction. If you realize that these two scenarios are responsible for most car-motorcycle accidents, you know that loud pipes are pointless.

Moreover, newer cars have gotten better in terms of noise-cancellation. The average sedan can keep out road noise as much as possible to ensure the comfort of occupants. Louder pipes will not increase your chances of being noticed by drivers.

Despite these, more Harley owners continue to increase the noise levels of their bikes to deafening limits. These riders disturb everybody, from road-users to residents, and give Harleys a lousy image. H-D, recognizing the negative effect of loud Harleys on its reputation, now advises users against tampering with the exhausts on their bikes.

Why Do Harleys Sound So Different?

Harleys are unique for many reasons, but it is the sound they make that truly stands them out.

For decades, Harley-Davidson has refined the signature sound such that no other bike sounds like a Harley. Many say, “you hear a Harley before you see it,” and nothing could be more accurate.

The secret of the unique sound of a Harleys lies in the design of the Harley-Davidson V-Twin two-cylinder engine. The pistons in most two-cylinder horizontal engines are timed to fire alternatively. This means one piston fires on each revolution of the crankshaft, i.e., every 360 degrees. The crankshaft usually has two pins, which are 180 degrees apart to which both pistons are connected.

The difference with the Harley V-Twin engine is that the crankshaft has one pin [instead of two] connecting both pistons. This, combined with the V-shaped arrangement of the cylinders, prevents both pistons from firing at intervals. What you get instead is the choppy, uneven, “pop-pop” sound that has become a signature element on Harleys.  

The “potato-potato” sound [as some call it] is a big part of the H-D image and a signature element of Harley motorbikes. The sound is so popular that Harley-Davidson tried patenting it in 1994.

Although the attempt was unsuccessful, the “potato-potato” sound remains a prominent Harley feature, and any bike that copies it risks being mistaken for a Harley.

How Loud Are Harleys Compared To Other Brands?

When you see a motorcycle with an ear-splitting exhaust tearing away, you automatically assume it’s a Harley.

With their loud engines, it is easy to conclude that every roaring bike on the road is a Harley. However, just because Harleys have a noisy engine/exhaust doesn’t make them the loudest bikes on the planet. Factory-produced Harleys are loud, but other bikes are just as loud.

In particular, cruisers made by the likes of Yamaha, Honda, and Suzuki, often have slightly lower or same decibel rating as Harleys. Models such as the Kawasaki Vulcan, Honda Shadow Spirit, Suzuki Boulevard, Moto Guzzi Audace, and Triumph Rocket all feature thundering exhausts like Harleys.

Anyone who owns a motorcycle, Harley or not, can decide to increase his bike’s decibel rating. That Harley riders are more likely to mod their exhausts doesn’t mean those who own other bikes don’t do so.

Owners of foreign-made cruisers often tune the exhausts on their bikes to make them sound like Harleys.

Are There Any Restrictions On How Loud A Motorcycle Can Sound?

Contrary to public belief, laws regulating the noise level of motorcycles exist.

The U.S. EPA Code, for example, limits motorcycles to a total noise emission level of 80 decibels. Motorcycle companies like Harley-Davidson test the noise level of their bikes to ensure they comply with EPA standards.

Furthermore, federal law requires motorcycle manufacturers to use only EPA-approved mufflers on their bikes. Such mufflers are embossed with a U.S. EPA muffler label, which law enforcement officials can easily recognize.

You are not to tamper with, modify, or replace the EPA-approved muffler on your motorbike during its life. The only exception is if the replacement muffler is an EPA-approved muffler. Using a non-EPA-approved muffler or removing your motorbike’s muffler is a punishable offense under the law. 

Law enforcement officials can arrest you if your bike’s sound level is above the limit specified in the EPA code. Police officers use the SAE J331a full-throttle drive-by testing procedure to determine the sound levels of motorcycles.

Usually, this involves using a sound level meter to monitor the decibel rating of your bike’s noise.

States have local laws and ordinances regulating the noise level of motorcycles. For example, California limits pre-1986 motorcycles to 83 decibels and post-1986 bikes to 80 decibels.

Punishment for contravening motorcycle noise laws also varies according to state. Police in some states issue only fines/tickets to offending riders. Other states are more stringent and may force the offending rider to remove the modifications or have his bike impounded.

Why Do Law Enforcement Ignore Loud Motorcycles?

Given the freedom riders on noisy bikes enjoy on public roads, it is hard to believe that there are laws restricting motorcycle sound levels.

People often question the effectiveness of noise laws, especially as riders rarely get booked for riding excessively loud bikes.

The problem is not that these laws are inadequate; the police department doesn’t have the resources to enforce them. Catching noise law offenders involves using sound meters to determine the sound level of bikes on the road.

Most PDs are unwilling to spend resources to buy sound meters or training officers to use them. Even when they do, they typically train a few officers who cannot cover large areas.

For example, individual counties used to have full-time officers patrolling streets searching for people riding noisy bikes. The program was quite successful and led to a reduction in the number of loud motorcycles on county roads.

However, most of these full-time officers were laid off after budget cuts forced police departments to downsize.

Cases like this underscore the need for increased resources and manpower to fight the scourge of extra-noisy motorbikes. Until states treat noise law offenses how they handle speed rule violations, riders will continue to terrorize others with their ultra-loud motorcycles.

Just as states give many officers speed radars and training to use them, they should give officers sound meters and train them to use the equipment.

Why Do Harleys Sound Like A V8 Engine?

The loud throaty noise Harleys make while idling has led some to compare them to the American muscle cars of old.

Unlike foreign-made motorcycles [which often have a high-pitched whine], Harleys emit a low powerful growl-like sound. This sound is quite similar to the sound of V8-engined sports cars when revved. But why do Harley engines sound like V8 engines? Let’s explain.

The different firing interval is the reason Harley engines have a V8-like sound. Harley’s V-Twin engine has two cylinders arranged in a 45-degree “V” configuration attached to a single-pin crankshaft. Since the pistons are sharing a pin, this causes the cylinders to fire at uneven intervals.

The process is like this:

  1. A piston fires
  2. Another piston fires at 315 degrees
  3. There’s a 405-degree gap.
  4. Another piston fires at 315 degrees
  5. The process starts all over again. 

Instead of getting an even “thump-thump” sound found in other engines, you get a “thump thump, thump thump” sound. This sound is strikingly similar to the powerful thumping noise made by V8 engines, hence the comparison.

Do All Harleys Sound The Same?

Although all Harleys share or at least run a variant of the original Harley 45-degree V-twin engine, they do not sound the same.

Older Harley “Big Twin” cruisers and tourers have the classic Harley engine note. Newer models? Not so.

In fact, a big reason for the unpopularity of the LiveWire among Harley’s core demographic was the un-Harley whirring engine sound. The classic engine note is part of the Harley package, and a different-sounding model will likely be unpopular.

Harley Davidson has implemented different styles of engines over the years. Each engine with its own unique sound.

For example, older Evolution and Shovelhead engine models have the distinct “potato-potato” sound. Whereas newer models with the Milwaukee-Eight engine will sound a little different but still have the distinct Harley Davidson rumble fans have come to know and love.

Custom pipes and adjusted tuning are another reason one Harley can sound different than another. Some Sportster or Street may opt to get drag pipes, but that’s something we’d advise against. Also, reducing your bike’s idle speed to get “that sound” will reduce the oil pressure. This limits the oil supply and may lead to significant engine damage.

Can You Complain Over Loud Motorcycles In The Neighborhood?

Loud motorcycles can be a pain, especially if you have neighbors who love idling their bikes every time, even in the mornings. You don’t have to endure loud noise levels every day, which is why the police exist.

You can go to your county or town’s police department to complain about the excessive loudness of bikes in your area. It helps if you quote local ordinance(s) in your complaint, too.

However, if personal complaints don’t work, consider getting your other neighbors to make a group complaint, either to the police or local/municipal authorities.

Local authorities/police may not act if you make a personal complaint. But if they find a large number of people lodging complaints concerning the same issue, they will be more inclined to act.

Final Words

Loud pipes do not save lives; neither do they make your bike perform better.

All noisy pipes do is annoy other road-users, neighbors, and people in the area.

If you want to protect yourself against accidents on the road, invest in a rider-training course to hone your skill and on-road awareness. And if you will ride loud Harleys, do so in a dedicated racetrack where you can make all the noise you want.

Riding a loud motorcycle in a residential area or on public roads is an infringement on the right of others to a noise-free environment.

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