Roadsitalia approved exhaust systems are developed and certified to meet the sound limits laid down for the vehicle models listed in the type approval. This page explains how exhaust noise is correctly measured, which regulations apply and how the result should be interpreted.
Regulatory references
- UN Regulation No. 92 — approval of non‑original replacement exhaust silencing systems for L‑category vehicles. This is the regulation under which our systems are approved.
- UN Regulation No. 41 — sound emissions of motorcycles; defines the measurement methods referred to by Regulation No. 92.
- Commission Delegated Regulation (EU) No 134/2014 — environmental and propulsion unit performance requirements (supplements Reg. (EU) 168/2013).
- ISO 5130 — international standard for measuring the sound level of stationary vehicles.
What is measured
Noise is checked in practice with the stationary vehicle test. This value:
- is stated on the registration document in field U.1, with the test engine speed in field U.2;
- is a reference figure for roadside and periodic technical inspections, not a stand‑alone approval limit;
- must not be compared with the drive‑by sound level (field U.3), which uses a different method (7.5 m, under acceleration) and gives markedly lower values.
For an approved replacement silencer, the conformity criterion is that it does not produce levels higher than the original system of the same vehicle, measured with the same method (UN Regulation No. 92, § 6.2).
How the measurement is carried out
The measurement must be carried out by a workshop or qualified personnel, with:
- a Class 1 sound level meter (IEC 61672‑1), calibrated, with a windscreen;
- an outdoor, flat area with no wall, vehicle or obstacle within 3 m of the vehicle or the instrument, and no bystanders nearby other than the operators;
- the microphone 0.5 m from the exhaust outlet, at the same height as the outlet, at 45°;
- the bike in neutral, engine at operating temperature.
Procedure: bring the engine to the speed shown in the vehicle documents, then release the throttle rapidly to idle. The maximum value is recorded over the period covering the brief hold at constant speed and the entire deceleration. The test is repeated 3 times; readings are valid if they do not differ from one another by more than 2.0 dB(A), and the highest is taken.
How the result is assessed
The stationary sound level shown in the vehicle documents is a reference value, not an absolute limit. UN Regulation No. 92 (§§ 3.3 and 8), under which the system is approved, allows the stationary test to deviate by up to 3 dB(A) from the approval value; to this is added the inherent uncertainty of a field sound‑level measurement, of the order of 2 dB(A). Taken together, differences of up to about 5 dB(A) from the stated value are to be regarded as normal and do not in themselves constitute a non‑conformity.
| Item | Reference | Value |
|---|---|---|
| Tolerance on the stationary test | UN Regulation No. 92, §§ 3.3 and 8 | up to 3 dB(A) |
| Uncertainty of a field sound‑level measurement | maximum spread allowed between the 3 readings | ≈ 2 dB(A) |
| Overall deviation to be regarded as normal | — | ≈ 5 dB(A) |
When a measurement is not valid
- readings taken with non‑professional instruments (Class 2 or generic sound level meters, without calibration);
- measurements at distances or positions other than those indicated;
- tests in enclosed spaces, near walls or vehicles, or with high background noise;
- measurements with the db‑killer removed or modified: in that case the conformity of the approval is void.
Do you have an abnormal reading?
If, measured under the conditions described above, the value is still abnormal, contact us attaching:
- a single, continuous video of the test showing the instrument (make and model), the microphone position, the engine speed on the tachometer and the value, with the full sequence speed → release → maximum value;
- photos of the silencers inside and outside;
- the km covered since installation.
The material will be assessed by our technical department in accordance with the applicable regulations.
References: UN Regulation No. 92 · UN Regulation No. 41 · Commission Delegated Regulation (EU) No 134/2014 · ISO 5130. See also: Roadsitalia Homologation Certificates.