Why are Dirt bike so loud?


Most of the time, you’ll hear loud thunder-like dirt bike roars near highways and residents, and you may be wondering why it’s always so noisy. Perhaps this is one of the questions you asked yourself and couldn’t find a suitable answer. Why are Dirt bike so loud? So here is a short answer to this. 

Dirt bikes are very loud and it can be due to many reasons such high revolution per minute (RPMs), short size mufflers, and the frequency of using accelerator. Normally 2 stroke dirt bike’s sound is louder than 4 stroke bikes.

What if your dirt bike makes such an unpleasant noise? How big do you think? Where do you think the noise comes from? And how can you reduce it? This article will help you answer these questions correctly and understand how to deal with this issue.

First, how loud is the dirt bike? There are several factors to consider when it comes to a dirt bike’s volume (decibels). These factors include the model and manufacturer of the dirt bike, the type of tube used to format the bike, and the RPM of the dirt bike.

In addition, the speed at which you ride the dirt bike determines the volume of the bike. Therefore, different noise levels can occur, depending on whether you ride your bike slowly or fast.

What is the speed of a dirt bike?

According to a survey conducted in California, the sound of dirt bikes should not exceed 96 decibels.

This value is about the same as a low roar and is the most pleasing sound recommended for all off-road bikes. However, each state has its laws regarding the use of dirt bikes.

Even if the decibels of all dirt bikes fluctuate from time to time, the level of noise generated depends entirely on the bike’s manufacture and the speed at which it rides the dirt bike.

These two factors can affect the performance of a dirt bike and its noise level.

Where does the noise come from?

Perhaps dirt bikes are making a lot of noise because of their high rpm (RPM), short muffler, and frequent acceleration instead of riding.

All of these are factors that can affect the noise of your bicycle. For example, a 2-stroke dirt bike is louder than a 4-stroke dirt bike, but a 4-stroke dirt bike is even louder. In addition to the silencer and engine speed, other factors affect the loud noise produced by dirt bikes. However, it is not easy to determine which of these factors, are the leading cause of the loud noise of a bicycle.

The bottom line is that they all contribute to the generation of noise in some way. For example, the most common sources of noise on dirt bikes are:

Revolutions Per Minute (RPM)

The sound of a dirt bike is highly dependent on the speed of the bike. For example, a two-stroke dirt bike will make noise depending on the movement of the adjustable power valve. This means that if the valves open at different speeds, the bike will produce varying noise levels.

On the other hand, the same noise level fluctuation occurs on a 4-stroke dirt bike, but this difference is due to the carburettor setting. In other words, noise is affected by the length and width of the carburettor.

Muffler and Pipe

Muffler and Pipe are the sources of the loud noise generated by dirt bikes. Depending on the type of dirt bike muffler, the noise may be louder. Examples of silencers are chamber silencers, turbo silencers and straight-through silencers. For the chamber silencer, the internal grooves cause some friction, which reduces the noise level. A straight muffler is a standard pipe that absorbs noise and reduces the noise it produces.

Finally, the turbo style muffler is shaped like an “S”, picking up most of the sound and pulling out the rest. However, when it comes to dirt bike pipes, things change. This is due to the different lengths of the tubes. This means a faster burst of energy from the bike.

This causes a lot of noise as more energy pulses escape from the pipe. In addition, short pipes produce a lot of loud noise, as opposed to long lines.

Wear and Tear

Different parts of the bike do not always make the sound higher or lower. In fact, like other parts of a dirt bike, old and used bikes can make more noise. In addition, as the bike gets older, some parts wear out and make unwanted noise while riding. Therefore, check and replace old and worn parts of your dirt bike to minimise such loud noises.

2 Stroke vs 4 Stroke which is larger?

Two-stroke and four-stroke dirt bikes differ greatly in the way their pistons move in the engine. The stroke is related to the number of times the piston moves back and forth in the engine, causing a chain reaction in the engine itself.

How are sounds made?

Noise is generated by the number of pistons in the engine pushing out the exhaust.

For 4-stroke dirt bikes, the term “4-stroke” is used because the engine follows a specific set of injection compression ignitions and exhausts. This is done effortlessly. The exhaust is released each time the piston is pushed down twice.

Exhaust gas, on dirt bikes with a two-stroke engine, combustion occurs each time the piston retracts. In other words, the engine makes a relatively loud noise compared to a 4-stroke dirt bike.

This new difference in the functionality of two-stroke and four-stroke engines is the main factor behind the noise generation. Therefore, a 2-stroke dirt bike is louder than a 4-stroke dirt bike.

How do you reduce the noise generated by dirt bikes?

If it works properly and the noise level is low, it doesn’t matter if the dirt bike is new or used.

If not, it’s best to turn down the volume while enjoying the ride to avoid confusing others. Wheels usually grow with age and occasional use.

This is the moment when you notice that some parts are worn or loose, producing unbearable noise or volume for you and everyone around you. To overcome the noise of the dirt bike, you need to take drastic action at the right time before it’s too late. First, check your bike’s muffler to see if it’s the cause of this unpleasant volume.

In most cases, a short muffler will cause the bike to make a loud noise. You can change all of this by fixing the problem to absorb most of the noise generated by the engine.

Then check all the parts of the dirt bike to find the details that need repair or replacement. Please make sure the tube is airtight and clip it in case something goes wrong. Check all the bolts and nuts on your bike to make sure they are securely fastened and there is no noise while riding.

Repair everything that can cause noise to ensure the overall performance of your dirt bike is the best. The most important thing is to ensure that the dirt works well and complies with city and state laws.

Does the Electric Dirt Bike Make a Noise?

The electric dirt bike is known to minimize the noise of motor hum, but it is hushed. Unlike petrol dirt bikes, these motors run on the electrical energy generated by the batteries attached to the bike.

To answer the above question, it is correct to say that electric dirt bikes make some noise, but their noise is too small to be perceptible.

This is the best reason to drive in a residential area.

4 Reasons Why 2-stroke dirt bikes Are So Loud

Have you ever wondered why 2-stroke motorcycles are bigger than 4-stroke motorcycles? I can’t drive my 2-stroke in my yard because my neighbours certainly complain. Here are 4 reasons to help make a two-stroke dirt bikes are louder than a four-stroke dirt bikes:

1: Two-stroke exhaust Sonics

Two-stroke engines do not have inlet and outlet valves to regulate the flow of fresh air into the combustion chamber and the flow of exhaust fumes from the combustion chamber. Instead, as the piston moves up and down the cylinder, it opens an opening in the cylinder wall through which air is drawn in and out.

Sound waves are reflected from a specially tuned exhaust to contain fresh air during the compression stroke. As a result, with each stroke (or combustion cycle), two sound waves are emitted from the exhaust, resulting in a higher frequency or pitch, resulting in a louder sound. This is also the reason why the two-stroke produces the familiar “hinhinhin” sound.

The 2-stroke exhaust is tuned to support combustion. With a 4-stroke engine is low and quiet because there is only one exhaust sound wave every other cycle.

2: Air-cooled engine is louder

Most 2-stroke motorcycles are air-cooled rather than liquid-cooled. This means that the cylinder wall is thin because there is no water jacket around the combustion chamber. In a liquid-cooled four-stroke engine, the engine’s explosion sound must pass through thicker cylinder walls and waterways before it can interfere with neighbours.

The air-cooled engine gets a larger air-cooled 4-stroke (like my Honda XR 650 L) and a liquid-cooled 2-stroke (like my Beta Rev3 trial bike), while the 4 is generally Liquid-cooling and 2-stroke air cooling.

3: Free-flow 2-stroke exhaust

Due to its design, 2-stroke engines do not have their exhaust stroke-like 4-stroke engines. Instead, the cylinder opens an exhaust port near the end of the power stroke. To quickly remove the burned exhaust, two-stroke motorcycles require free-flowing exhaust to clean the combustion chamber.

Free-flowing exhaust is larger than muffled pipes. Another reason for free-flowing exhaust on 2-stroke motorcycles are to keep weight low. Dirt bikes often use a two-stroke engine to ensure the maximum power-to-weight ratio in races and jumps.

Free-flowing exhaust is much larger than restricted exhaust with a silencing muffler. For this reason, almost all street-legal motorcycles these days have four strokes. A four-stroke engine can operate properly with a limited amount of exhaust gas, resulting in lower carbon monoxide emissions. Due to the strict emission regulations introduced every year, road bikes equipped with 2-stroke engines are no longer seen.

4: Two-stroke has no valves

2-stroke motorcycle engines do not have intake and exhaust valves like 4-stroke engines. Also, the exhaust gas output of the cylinder wall opens towards the end of the work cycle, exposing the outside world (and ears) to a small explosion in the combustion chamber.

In a 4-stroke engine, the valve closes entirely during the whole working stroke and opens only when the piston in the cylinder rises again. When the exhaust valve opens, the explosion inside the engine ends, and only the exhaust gas comes out of the exhaust pipe.

Conclusion

Dirt bikes make loud noises for various reasons, including acceleration, displacement, silencer type, pipe length, wear, and the number of engine piston movements.

The noise level generated by these bikes is also determined by the particular model, brand, bike format, and speed.

The good news is that you can limit the noise your bike makes by checking and replacing worn parts and making some changes to important noise-related details.

Thomas A. Talley

I’m Thomas. Since childhood, I am fond of bikes and hence dirt bikes are my passion now. Ever since then, I’ve been giving advice to the beginners and this has become my hobby.

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