One of the most common characteristics that are attributed to Harley Davidson motorcycles is how loud they are when you encounter them on the road. For some this can be seen as a nuisance, for others it is something that they actively strive for.
You might be wondering why exactly Harley Davidson motorcycles are so much louder than other motorcycles you encounter on the road. This is a common question and actually has an answer that you might not suspect.
Harley Davidson motorcycles are louder than other bikes because they have been specially altered and modified to increase their sound level when running. It is a common misconception that Harley Davidson motorcycles are made loud when in reality they have been customized by the user to exceed the standard decibel level.
This guide will explain this in more detail, as well as some other common questions that people have regarding why Harley Davidson motorcycles are so loud. There are many different methods and factors that come into play when detailing the different ways and reasons someone would make their Harley Davidson louder.
Table of Contents
What Makes A Harley So Loud
Harley Davidsons is commonly modified to exceed the factory standard 80db limit by the users after purchase. Taking into account the aftermarket modifications that are extremely common with most Harleys and the above-average noise decibel level that it emits using the standard factory setup, it makes for an extremely loud bike.
The most common modifications that Harley owners make on their bikes to increase the decibel level are to remove the muffler, replace the stock exhaust pipes with aftermarket variants, and in some cases replace the whole exhaust system with one that is more powerful and thus louder.
To give some frame of reference, the average car emits a decibel level of 55db. This makes the stock decibel level of most Harley-Davidsons, which is 75db, significantly higher than the average car. Once aftermarket modifications have been made, this number could jump up to over 125db, which accounts for how blisteringly loud some Harley-Davidsons can be when revving up.
That being said, Harley Davidson has been known to support aftermarket modifications that enhance the decibel level significantly. They do this by sometimes offering special modification packages that the user can bundle when they purchase their bike.
In recent years, however, Harley has moved away from supporting the practice of modifying the exhaust system on their bikes. In some cases, exhaust modification could void the warranty on your bike, causing your to have to front the bill for any repairs that might become necessary over the years.
How Loud Are Harley Davidson Motorcycles Compared To Other Brands?
The next part of this guide will compare some other popular motorcycle brands and their average decibel level with that of Harley Davidson. You can use the table below to make side-by-side comparisons so you can see for yourself how other bikes stand up to Harleys in regard to noise levels.
As the table will show, Harley Davidson’s standard factory noise level exceeds the average of all of the most popular motorcycle brands currently on the market. After modification, the noise level could double that of some popular brands. This is the reason that Harley-Davidsons are so noticeable on the road.
| Brand | Avg. Noise Level |
| Harley Davidson | 80db (Factory) – 125db (Modified) |
| Honda | 67db |
| Indian | 66db |
| BMW | 72db |
| Kawasaki | 75db |
| Yamaha | 68db |
| Suzuki | 76db |
Why Do Harley Owners Want Their Motorcycles Louder?
Loud exhaust pipes are part of the Harley Davidson image, which is why so many Harley owners modify their bikes in a way that drastically increases how loud they are. In the past, Harley riders have justified the intentional increase in noise level by attributing the loudness as a safety measure.
By this reasoning, the louder your bike is, the more likely you are to be noticed by other vehicles around you on the road. That being said, as cars become more advance and adequate at noise canceling, this reasoning becomes less sound.
You are not more likely to be noticed by someone driving a modern car due to the noise level of your motorcycle. This reasoning was coined the “Loud Pipes Saves Lives” theory and can attribute to much of the noise modification that Harley owners have utilized over the past few decades.
Another common reason that Harley owners give for modifying their bikes so they are louder is that they help improve performance to some degree. This has also been losing ground in the past few years as many mechanics have come forward saying that louder exhaust pipes do not have a significant effect on performance and in some cases, might hinder performance.
Even in spite of this new information, Harley owners still commonly modify their bikes to be louder to maintain the image and prestige that comes with owning and riding a Harley. That being said, Harley Davidson has recognized the negative impact that modified bikes that exceed the decibel limit can have on their brand.
They have recently begun advising again to modify the exhaust system on their bikes and have even gone so far as to void warranties for bikes that have been too heavily modified. You should be careful when modifying your own Harley, as it could lead you to expensive repair bills if you happen to void your warranty during the process.
Other Motorcycle Guides
Are Loud Harleys Legal?
While it might not seem like it, there are legal restrictions and consequences set in place for motorcycles that exceed the 80db noise limit. In the United States, the EPA Code set this limit for all motorcycle noise emissions and requires that all manufacturers adhere to these limitations.
The law also states that motorcycle owners are not to replace or modify the EPA-designated muffler that comes preinstalled on all motorcycles. The only way that you can legally replace or modify your muffler is if the new muffler is also EPA-approved.
If your bike is too loud, you could be at risk of law enforcement issuing you an expensive ticket that you will have to pay. Too many repeat offenses could cause you to be arrested in some rare circumstances. Law enforcement has access to sound measuring tools that can help determine if your motorcycle is within the decibel limit.
If your bike is determined to be out of the acceptable noise limitations, you could risk being issued a ticket or having to have your modifications removed before you will be able to legally drive your bike. That being said, it is actually quite rare for law enforcement to actively monitor the sound level of motorcycles in recent years.
Due to the expenses involved in arming law enforcement with sound measuring tools and actively assigning officers to patrol areas for sound violations have simply not been viable in recent years. There could be more advanced technology that law enforcement could utilize in the future to catch riders who have modified their motorcycles to be louder than the acceptable levels, but that is likely far into the future.
Final Thoughts
This guide has provided you with all of the information required to better understand why Harley Davidson motorcycles are so much louder than other motorcycles on the market. As this guide has indicated, this is not an intentional design but the result of aftermarket modifications that significantly increase the decibel output of the bike being modified.
Aftermarket modifications are extremely common and are often one of the first things that Harley Davidson owners will be thinking about after purchasing their bike. Keep in mind that if you are interested in modifying your Harley so that it is louder, you could be at risk of getting a ticket.
In general, it is not the best practice to modify your Harley in a way that increases the decibels. Not only will most people you encounter consider it a nuisance, but it could also lead to your motorcycle underperforming due to the modifications that it has undergone.
You should be conscientious of others around you and keep your motorcycle at the designated noise level. This can help you avoid issues with the police and issues with your motorcycle. Using the information in this guide, you can now be more informed as to the reasoning behind loud Harleys, as well as the methods that owners use to produce the increased noise level. Next time you hear a Harley coming from several yards away, you will now know why.
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I’m William Guzenski, ASE certified master automobile technician & automotive expert. I love to attend race events and car shows throughout the country. I also loves to travel 40-foot motorhome, exploring abandoned mines and ghost towns. I’m currently building another car for Bonneville Salt Flats and will be campaigning a drag car at several events.