FIM PLANS TO LOWER SOUND LIMITS IN 2008: WHAT’S WRONG WITH AMA TESTING?

The recent FIM Congress has announced a plan to lower its current 96 dB/A sound limit to 94 dB/A (measured at fixed rpm) in Motocross by 2008. The new American standard is 99 dB/Aalthough the two testing scales are not comparable.

The main problem with the current sound testing, both at the AMA and FIM levels is that they are done incorrectly. What good does it do to test a 450cc motocross bike at 4800 rpm, when it is ridden at twice that rpm. And, it has been proven that the manufacturers are able to produce bikes that are quieter at the fixed rpm than the year before’s model, but louder above the fixed limit. Which means that instead of bikes getting quieter, they are actually getting noisier. Until the AMA (MXA doesn’t care how the FIM sound test bikes) sound test bikes at the speeds in which they run, with actual passes past a sound meter, the whole subject is nil. As for current sound testing procedure, it may be in the AMA rule book and everyone at an AMA race may have to go through sound testingbut it’s not the right way to do it. It’s a waste of time.

The AMA should use the same system that most municipalities across the country use, which is a set decibel level at a specific distance (most typically used in court cases is the “75 decibels at the property line” rule). The AMA could set up a sound meter and have every bike make a pass at full throttlefrom these tests they could choose a decibel level that would be accurate and quietnot fake accurate and fake quiet. In addition, the AMA could institute random sound tests on bikes that seem objectionably loud while they are on the race track.

But, testing a bike at rpm that is less than half of the engine’s max rpm is stupid. Yes, it is sound testing, but not of the actual sound produced. It is “lip service sound testing” of bikes at half throttle. It is not real world. It is not a true test of a bike’s sound. It just sound testing to keep some bureaucrat busy.