Those beginning their journey into the world of motorcycles must familiarize themselves with the unique vocabulary used in this subculture, filled with terms and phrases that aren't included in the dictionary.

In this regard, if we ask at ACMOTOS what a Db Killer is to an experienced biker, they would answer without a second thought. However, an uninformed beginner might be baffled by such a question.

So, let's explore what this component is, its purpose, and how it functions.

What is a motorcycle's dB Killer?

The term dB Killer comes from “dB” (abbreviation for decibel, the physical unit that expresses the level of sound intensity) and the English word “killer” (murderer, slayer). Thus, it can be literally translated as “decibel killer” or “decibel slayer”.

Several disassembled exhaust pipes showing dB-killer

So, what exactly is a dB Killer? It's a device placed inside the final part of the exhaust pipe whose purpose is to significantly reduce the sound level coming from the engine. In other words, it's an exhaust silencer.

How does a dB Killer work?

The motorcycle's dB Killer is a hollow metal tube, whose external diameter is smaller than the inner part of the exhaust's end. The dB Killer is situated within the exhaust's final section.

Structurally, the inside of the dB Killer consists of a combination of cores and/or perforated sheets whose purpose is to prevent the free escape of gases originating from the engine.

dB killer disassembled

When the gases pass through these cores or inner sheets, they undergo turbulence and changes in direction, which results (in synergy with the narrowing of the exhaust pipe) in a significant noise reduction.

Is it legal to remove the dB Killer from the motorcycle?

At ACMOTOS, we're aware that many two-wheeler owners choose to forgo the dB Killer, believing the motorcycle's sound is much purer or more alluring without it.

In this context, currently, there's no law or provision that prohibits a motorcycle owner from removing the dB Killer.

However, European motorcycle and exhaust pipe manufacturers' associations have recently signed an agreement that encourages, in line with EU ambient noise policies, the manufacturing of exhaust pipes where removing the dB Killer is either extremely hard or technically impossible.

In conclusion, it's entirely legal to ride a motorcycle that has had its dB Killer removed, as long as the sound emissions do not exceed the maximum limit set by regulations.

motorcycle viewed from the rear showing exhaust pipes

What does the new regulation say?

At this point, the DGT (General Traffic Directorate) has recently toughened the rules regarding noise levels emitted by motorcycles and other motor vehicles. These changes have been effective since January 2, 2023.

The DGT states that, besides preventing potential disturbances or scares to pedestrians, residents, and other drivers, the aim is to eliminate the proven risk to traffic safety from driving under excessive noise.

In this regard, a maximum sound threshold of 87 dB has been established for any motor vehicle. Penalties will be enforced when the readings from sonic measuring equipment exceed the threshold by 4dB. In other words, there will be a penalty if the measurement exceeds 91 dB.

An interesting fact is that this 87 dB limit doesn't only apply to noises from the engines but also includes sonic emissions from added vehicle accessories (like sound systems and megaphones).

Lastly, from ACMOTOS we'd like to add that the financial penalties are quite alarming: the minimum fine is 100 euros, but depending on the detected noise excess, it can rise up to 3.000€, especially if the violation is particularly severe and there's a recurrence.

Alternatives

We know it can be a hassle to have to dismantle these types of devices, whether out of fear of breaking them or possibly facing penalties. For that, we have alternatives like the silencers from Ixil Exhaust, a well-known Spanish brand, due to its presence in MotoGP and its high-quality exhaust systems.

motorcycle exhaust black color of Ixil Exhaust

There are also devices for lovers of classic and custom motorcycles, under the name of Ironhead, whose range inherits the experience and same quality as Ixil Exhaust.

black motorcycle exhaust by Ironhead

And here is our today's post, we hope it has helped you to know everything about the dB Killer, if you have any questions about the exhausts do not hesitate to contact us, greetings and until the next article!

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