Why are motorcycles so loud? First, we have to clarify that stock motorcycles are not extremely loud. However, it’s also a fact that many of them produce more noise than the average car. Why? In a nutshell, there are five main factors influencing how loud motorcycles are:
- Special engine features (design, layout, compression, performance)
- Small stock mufflers and short exhaust pipes
- Marketing considerations
- Aftermarket exhaust systems and performance modifications
- Aggressive riding style and showing-off
If you want to find out more about these factors, you are in the right place!
Why Do Motorcycles Sound So Loud?
Before we drill into the details it has to be mentioned that not every motorcycle is disturbingly loud. There are many different bikes out there, and each model produces a different sound.
You can find many silent motorcycles on the roads, but they just don’t attract much attention. But generally speaking, people consider motorcycles to be louder than other vehicles for some reason.
Without further ado, let’s take a closer look at the causes and factors!
Different Engine Features
Let’s face it, motorcycles are overly loud because they are primarily designed for thrilling adrenalin rushes and thrill rides.
Although you can find some smaller bikes for general use like commuting, the majority of them are built for performance-minded buyers.
And what are they looking for? Many are seeking nothing more than higher performance and a great sounding exhaust.
To satisfy customers and make motorcycles more desirable, manufacturers have developed many different engine layouts over the years.
Surprisingly, some of them are quite silent. For instance, many lightweight motorcycles are powered with smaller engines that put out a moderate level of noise.
In contrast, bigger bikes generate significantly louder exhaust sounds. The engine of these machines typically features a V-twin or an inline-four layout, which makes them much louder than their smaller brothers. Why?
Because of their bigger displacements, higher HP ratings, and different designs.
Let’s start with the V-twin engine configuration, where you can find two big pistons in the engine in a V-shape. These engines can be found in virtually every Harley-Davidson and many other cruiser motorcycles.
These engines run at low RPMs and produce the easily recognizable “pop pop pause-pop pop pause” sound, which is actually dozens of mini explosions in every single second. The two heavy pistons work (and sound) like hammers in these engines, which is why V-twin bikes are so loud.
Another popular motorcycle class is the Japanese superbikes.
The majority of these machines feature inline-four engines, which means they have four cylinders in one row. These pistons are smaller and only go a short distance, which leads to high RPMs, extreme HP ratings, and finally a screaming noise.
While you can find many cars with inline-four engines on the market, the pistons in their engines are longer and go longer distances. This results in much lower RPMs and engine power.
While the average four-cylinder car engine runs at 2,000-5,000 RPM, many sportbikes only become lively above 7,000 RPM. On top of that, most of them can even reach 12,000-16,000 RPM.
As you might assume, these sportbikes are much louder and generate a higher frequency noise than all the cars around them.
Regarding cars, most are designed for comfort, so manufacturers try to reduce engine noise as much as possible.
To this end, they feature fuel-efficient, multi-cylinder engines that are typically water-cooled. These power sources sit in an enclosed compartment surrounded by plastic, insulating material, and a metal body.
Unlike cars, motorcycle engines are completely exposed and many of them still feature air-cooling. Although these are not the main factors, they also make motorcycles louder than cars.
Small Mufflers and Short Exhaust Pipes
Just like engine features, the design of the exhaust pipes and mufflers is no less important.
Another reason why motorcycles are so loud is that they have a smaller and simpler exhaust system than cars.
Thanks to their huge body, cars can house long exhaust pipes with zigzags, much bigger mufflers, and many other components, like a catalytic converter. What’s more, many of these parts are hidden under the car. Consequently, they can effectively dampen the engine noise.
But the main drawbacks of these systems are that they are huge, heavy, and costly. This is why motorcycles require a much simpler exhaust system, which is much less efficient.
Marketing Considerations
Other important factors are the psychological and marketing considerations. Although manufactures would be able to design quieter motorcycles, they still design them to be loud, and with good reason.
They understand that a nice exhaust sound can influence emotions and finally purchasing decisions. This is because the sound of a motorcycle is like music to many motorcycle enthusiasts.
And for many of them, the louder the better!
This is why manufacturers try to make the sound of many bikes as loud as possible. As long as it meets legal noise limits, the bike can go into mass-production without any issues.
However, as you will see, in most cases it is not the inefficiency of stock mufflers that make motorcycles disturbingly loud!
Aftermarket Exhaust and Performance Modifications
Just like snowmobile or jet ski owners, motorcycle riders are also prone to installing many aftermarket modifications on their machines, and aftermarket exhaust systems are no exception.
Riders can replace the exhaust on their bikes for many different reasons, but the most common are typically as follows:
- They are not happy with the sound/design of the stock muffler and want to customize their bikes. (This is typically the number one reason for this modification.)
- The stock muffler is damaged, so they are looking for a cheaper/more available replacement.
- They believe they can crank out some extra HP from the engine in this way.
- They want to make the bike noisier as they believe it makes them more noticeable to other drivers.
Whatever the reason for doing this, it’s safe to say that the majority of aftermarket exhaust systems produce louder and more aggressive sounds compared to stock units.
If you do some quick research on YouTube, you can find tons of review videos about aftermarket mufflers. Most of these videos compare the sound of many different mufflers mounted on the same bike to help the buying decision.
While some of them can keep the noise below noise limits, others make the motorcycle too loud.
These mufflers are typically sold as “for closed-course only”/ “off-road use only,” meaning that they are illegal to use on public roads.
But as you might assume, a lot of motorcycle owners install these not street-legal motorcycle mufflers on their bikes and ride them everywhere.
What’s more, some riders completely remove the muffler from their bikes, which is a configuration known as “straight cut pipes.” These bikes are not only extremely loud but illegal as well in many states.
We also have to mention the other various performance modifications. In most cases the main goal of these modifications is to get more engine power, but as a side effect they make the motorcycle much louder.
For instance, opened carburetors always mean higher engine sound.
Aggressive Riding and Showing-Off
Another reason why many people believe that motorcycles are much louder than cars is the attitude of the riders.
Generally speaking, cars are used for “regular” transportation, meaning that drivers just want to get from point A to point B comfortably and safely.
Therefore, they are more likely to follow the rules and avoid reckless driving (or, at least most drivers).
But when it comes to motorcycles, nearly all of these machines are toys rather than commuter vehicles. This means many of them are ridden hard and aggressively, which typically include speeding, reckless riding, and quick “race style” accelerations.
What’s more, irresponsible riders are also prone to doing tricks like wheelies or burnouts, even if these are illegal on public roads.
These stunts and riding styles not only carry a lot of risks but are also accompanied by very loud exhaust sounds.
To makes things worse, many riders like revving their engines up at traffic lights, or in parking lots.
Why are they doing this?
First, these engine sounds give a feeling of power, so many riders do this just for fun.
But there is no question that so many riders make a lot of noise just for attention, so they try to be as loud as they possibly can.
Of course, people tend to show off with their power sport vehicles, and motorcycle owners are no exception.
But while snowmobiles run on trails and jet skis out on open waters, motorcycles are around us. They can wake up an entire neighborhood in the middle of the night, and scare dogs and children.
On top of that, many riders directly scare pedestrians with loud exhaust sounds, sometimes to alert them and sometimes just for fun.
Disclaimer: Of course, we’re talking here about a small percentage of the motorcycle community. But it seems the public tends to judge motorcycles solely by these cases, as they don’t notice all the other bikers who ride reasonably!
Sadly, it seems a smaller group can ruin the reputation of the entire motorcycle community.
How Many Decibels Does a Motorcycle Produce?
Depending on their design and features, motorcycle noise levels vary widely. But generally speaking, the majority of motorcycles produce around 65-80 dB while idling. When it comes to riding, at 35 mph you can expect 85-95 dB, which climbs to 100-115 dB at full throttle.
Again, these are pretty average numbers, as motorcycle decibel level depends on countless factors. Newer motorcycles are generally quieter because of the lower noise level restrictions.
In contrast, the decibel level of the average car is 35-45 dB while idling and 50-60 dB at highway speeds.
For further reference, lawnmowers average about 90 dB while a jet airplane generates about 120-140 dB.
How Far Away Can You Hear a Motorcycle?
Many people find motorcycles annoying because their exhaust noise is heard far away. For instance, you can hear a motorcycle more than 3 miles away if it produces 120 dB. When it comes to quieter bikes, you can still hear 100 dB from about a mile away while you can hear 80 dB from 500-600 feet. (But keep in mind that the exact distance depends on many factors like the topography, and other environmental conditions.)
This is why the sound level of a motorcycle is so important. Since they can be heard from long distances, they can scare babies and dogs, and disturb patio conversations.
The other complaint against motorcycles is that they make so much noise in the mountains and woods. Many people visit these places to relax, and loud motorcycles can easily ruin their time spent outdoors.
Motorcycle Decibel Chart
To get a better idea of how far you can hear a motorcycle, we’ve put together a motorcycle decibel vs. distance chart.
| Feet | Miles | Sound Level 80 dB | Sound Level 100 dB | Sound Level 120 dB |
| 3,28 | 0,001 | 80 | 100 | 120 |
| 6,56 | 0,001 | 74 | 94 | 114 |
| 9,84 | 0,002 | 70 | 90 | 110 |
| 16,39 | 0,003 | 66 | 86 | 106 |
| 32,79 | 0,006 | 60 | 80 | 100 |
| 65,57 | 0,012 | 54 | 74 | 94 |
| 98,36 | 0,019 | 50 | 70 | 90 |
| 163,93 | 0,031 | 46 | 66 | 86 |
| 327,87 | 0,062 | 40 | 60 | 80 |
| 655,74 | 0,124 | – | 54 | 74 |
| 983,61 | 0,186 | – | 50 | 70 |
| 1639,34 | 0,311 | – | 46 | 66 |
| 3278,69 | 0,622 | – | 40 | 60 |
| 6557,38 | 1,243 | – | – | 54 |
| 9836,07 | 1,865 | – | – | 50 |
| 16393,44 | 3,108 | – | – | 46 |
(Source) To be used for informational purposes only! Exact distances may vary depending on many factors.
How Loud is Too Loud for a Motorcycle?
Common sense says that anything over 85 dB is too loud for a motorcycle. Why? Because extended exposure to this sound intensity can lead to hearing loss! This means that this and higher decibels can be too loud for the motorcycle rider and others on the street. This is why there are legal noise limits for motorcycles in many states.
Let’s take a look at them!
What is the Legal Decibel Limit for a Motorcycle?
The legal decibel limit for motorcycles is about 80-100 dB in most states, but surprisingly there are still many states that don’t have any laws restricting this. The legal noise limit for bikes not only varies from one state to the next, but many local governments and cities may have their own laws and regulations.
So, if you are considering modifying your bike’s exhaust system, always carefully check federal, state, and local laws to stay legal.
Keep in mind that a motorcycle exhaust that is too loud not only bothers others but can easily end in an expensive ticket.
Are Loud Motorcycles Legal?
Yes, unfortunately loud motorcycles are legal as long as they stay below the legal noise limit. But the good news is that manufacturers typically consider the lowest noise limits and design the bikes to that, so they can legally run in all states.
Also, reflecting the increasing complaints about motorcycle noise, more and more states are lowering the applicable legal noise limits.
This is why newer motorcycles are quieter compared to older models.
Which Bikes Have the Loudest Sound?
The loudest bikes are the “straight pipe” cruisers with unmuffled engines. These motorcycles can even put out 100-125 dB, which is pretty loud! Regarding stock bikes, anything with a large-displacement V-twin, or inline-four engine tends to be very loud because of their engine design and performance. Besides street-legal machines, you can find some of the loudest machines on race tracks as the limit for MotoGP bikes is 115 dB (previously, 130 dB!).
FAQs About the Loudest Bikes
Which superbike is the loudest?
The loudest superbike is the supercharged Kawasaki Ninja H2R, as it provides 118 dB with stock mufflers. With an aftermarket Akrapovič exhaust system it can be reduced to 98 dB.
How loud is a stock Harley exhaust?
The noise of a stock Harley exhaust is no more than 80 dB due to U.S. EPA regulations.
Which are the loudest Harley-Davidson pipes?
The loudest Harley-Davidson pipes are probably the “Short Shots” Exhaust Drag Pipes.
Are all Harley-Davidsons loud?
No, the good news is that not all Harley-Davidson motorcycles are loud, as you can now find electric Harleys on the market, which are really quiet!
Do quiet motorcycles exist?
Yes, recently more and more quite motorcycles are hitting the market, which are powered by electric engines.
Are electric motorcycles silent?
Contrary to popular belief, electric motorcycles are not completely silent. Although they generate far less noise than regular bikes, their engine, drivetrain, and wheels still produce a noticeable sound.
How can you make your motorcycle quieter?
You can make your motorcycle quieter by installing a “buffer” in your exhaust system or replace it with a more silent aftermarket muffler.
Conclusion
The main reason why many motorcycles are louder than cars is that they feature different engine designs, simpler exhaust systems, and they usually have some aftermarket modifications.
Generally speaking, motorcycles in stock condition are not extremely loud, as there is a legal noise limit for them in most states.
But unfortunately, many riders modify their bikes to make them sound better and louder. This generally means installing an aftermarket exhaust system, or even completely removing the stock muffler. Both of these solutions make motorcycles very loud!
What’s more, many owners ride their motorcycle aggressively, which often means doing quick accelerations, stunts, speeding, or just revving the engine at red lights.
All of these are typically accompanied by loud exhaust sounds, which can be very annoying for others!
References:
https://www.motorcyclecruiser.com/motorcycle-hearing-protection-earplugs-street-survival/
http://www.todayifoundout.com/index.php/2015/11/harley-davidson-motorcycles-loud/
https://www.kama.co.za/sounds-sirens/
