The facts behind the Euro 4 standard for motorcycles

More about the complete test

With an Euro 3 test the passing speed needs to be 50 km/h and is given full throttle at the line A-A (10 meters for the microphone). At line C-C, the throttle may be left loose again. Throughout the section, the maximum sound value is measured. This measurement is then also carried out in the 2nd and 3rd gears. The outcome is determined by the average of the total. This sound value must be lower than 80 dB (A).

In addition to the dynamic measurement, a static measurement is carried out. (The police can perform this test as well). The static measurement is a reference measurement. If the exhaust meets the dynamic measurement, the sound is recorded at the static measurement near the engine at half throttle (half the speed at which the engine delivers its maximum power). To test this, a sound meter is placed at an angle of 45° at 0.5 meters away from the exhaust tip. Finally, the motorcycle is put on a dynamometer where the power should not exceed +/- 5% from the original version.

And then Euro 4…

The static measurement remains the same with the Euro 4 level. But the dynamic measurement differs. The maximum noise value is reduced from 80 dB (A) to 77 dB (A). Now it is important that we drive precisely 50 km/h along the microphone. We have a deviation of +/- 1 km. For us to hit exactly 50 km/h we have to drive up at a slower speed. This ‘drive up’-speed is put on the motor frame. It also states in what gear we need to go. (For our Suzuki SV650, this was 38.9 km / h in 4th gear). Going full throttle between the lines A-A and C-C, the acceleration is measured.

Is the deviation of the acceleration too big? Then a measurement is needed in the gear where the deviation is too small and another measurement in which the deviation is too large. However, should we go back to the second gear, we should maintain a maximum noise level of 78 dB (A)! Does everyone still understand it?

The acceleration directly depends on the weight and, therefore, the weight of the test driver is also set at 75 kg with 5 kg of measuring equipment. These values are all entered into the computer, which calculates the acceleration. To rule out any cheating, various measurements (ASEP requirements) are performed at different speeds with increments of 5 km/h. We also check if the power or sound doesn’t show any dips. Finally we create a pressure and power measurement. Back pressure and power should not deviate too much from the original.

If all tests are successfully completed we get a verification code that we need to place on our products. Because these test procedures take so long, expensive equipment is needed and all the work there is involved, we, at BOS Exhausts, find it so important that end-users can purchase an approved exhaust that actually meets the new standards.