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Troubleshooting > Failures par brand > DERBI > My motorcycle 50cc DERBI makes noise, what to do?

My 50cc DERBI make noise

The sound of your 50cc motorcycle DERBI should not exceed 80 decibels (approximately). This indication is marked on the frame of your machine. If the decibel count is higher, you may be fined. All recent motorcycles (since 2007) are homologated with a pot to antipollution standards Euro 3, 4 or 5) and at sound levels compatible with the anti-noise law of 1992. All motorized two-wheelers must in theory respect a maximum level of sound emission:

• 72 decibels (dB(A) up to 50 cm3

• 79 dB(A) from 80 to 125 cm3 cm

• 80 dB(A) for those over 500 cm3

Le exhaust is the loudest part on a 50cc motorcycle.

It must be in good condition (without holes) and well fixed.

It should be noted that the smaller the cartridge, the louder the noise, the gases being expelled faster.

In the event of an anomaly in the exhaust system, two types of noise can be heard: that of metallic vibrations, knocking, or that of the engine, but more important than usual, more deaf.

ma AGM grazes at low speed

The anomaly comes from the fixing of my 50cc motorcycle DERBI

It is possible that a bride or that the hanging brackets are broken, that a buffer worn out is no longer able to dampen the vibrations between the body and the line or that the inside of the catalytic converter is broken. These symptoms cause vibrations

In the case of unusual engine noise, a cracked or holed exhaust is likely the cause, often in the tube upstream of the muffler or the muffler itself. a vulgar small metal part not repaired in time can lead to the replacement of the entire exhaust line, an annual check or every 20 thousand km is welcome.

In general the silencer, the last bulky element of the exhaust line before the end cap, can have a lifespan of up to 100 km. Long road trips are less harmful to the exhaust than short city trips where the condensation produced in the line is not eliminated. This is a corrosion factor: the water remains inside the exhaust, stagnates and corrodes the inside. This leads to the perforation of the exhaust.

If there is a leak on the exhaust line of my 50cc motorcycle DERBI

If there is a leak and the gases can escape upstream of the exhaust tip, it is therefore better to replace the defective parts of the exhaust line. exhaust, taking care to select the right equipment: some, aftermarket, less expensive and made of finer materials, have a shorter lifespan. There are also solutions for repairing perforated, split or cracked exhausts. Brands offer putty to seal the holes (less than 10 € the tube). But beware, these are temporary solutions that will only last a few thousand kilometres.

ma AGM grazes at high speed
ma AGM grazes at mid-speed

How to limit the noise of my 50cc motorcycle DERBI ?

For the pot, the first thing to change the Rockwool or replace this par steel wool (this technique limits the performance of your machine).

Le silencer of your 50cc motorcycle DERBI starting to age? Depending on your taste, opt for a very resistant aluminum muffler, or carbon and Kevlar to promote lightness. Pay attention to the fixing on the body of the pot, which can vary according to 3 or 2 screws.

The exhaust silencers are quite simply equipped with perforated grilles covered with absorbent materials. Par against the level of noise attenuation is not the best, we suggest you put an attenuator or "dB Killer (plays the role of chicanery).

Why install a db killer(chicane) on my 50cc motorcycle DERBI ?

Inexpensive motorcycle part to comply with French anti-noise law. the DB killer is very easy to install; often clipped or riveted to the gas outlet of the motorcycle silencer. It will take you 5 to 10 minutes for a noise gain ranging from 4 to 8 decibels.

Warning: if your motorcycle exhaust is not homologated, this motorcycle part does not make it homologated.

ma AGM grazes at mid-speed

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