The Society of Automotive Engineers (SAE)
International has produced a simple, consistent and economical
sound test standard that can be used to determine whether a street bike (on-highway motorcycle) exhaust system
emits excessive sound, the American Motorcyclist Association (AMA) reports.
The J2825 “Measurement of Exhaust Sound Pressure
Levels of Stationary On-Highway Motorcycles,” issued
by the SAE in May, establishes instrumentation, test site, test conditions, procedures, measurements and sound
level limits. According to the SAE, the J2825 standard is based on a comprehensive study of a wide variety of
“The motorcycling community and law enforcement
have long sought a practical field test for measuring street
motorcycle exhaust sound,” said Ed Moreland, AMA vice president for government relations. “Thanks to the
hard work of the Motorcycle Industry Council, and the SAE engineers involved in the project, for the first time
a simple field test is now available.
“The AMA maintains that few factors contribute
more to misunderstanding and prejudice against street riders
than excessively noisy motorcycles,” Moreland continued. “With the new SAE J2825 standard, street
motorcyclists can now determine how quiet, or loud, their bikes really are.”
Moreland added that the new standard follows a
template established years ago with the SAE J1287 off-highway
motorcycle sound test, a standard recommended by the AMA wherever off-highway motorcycles are operated.
The SAE J2825 on-highway motorcycle sound test
procedure is similar to the one used for the SAE J1287
off-highway motorcycle test. The street bike measurement requires holding a calibrated sound meter at a 45-degree
angle 20 inches from the exhaust pipe of a running engine. The procedure spells out how to do the test with the bike
at idle, at a predetermined engine speed (“Set RPM Test”), or by slowly increasing the engine speed of the bike,
known as the “Swept RPM Test.”
The SAE J2825 standard, prepared by the SAE
Motorcycle Technical Steering Committee, recommends a
decibel limit of 92 dBA at idle for all machines or — using the Set RPM or Swept RPM Test — 100 dBA for
three- or four-cylinder machines, and 96 dBA for bikes with fewer than three or more than four cylinders.
The creation of a new street motorcycle sound
measurement procedure was a top recommendation of the 2003
National Summit on Motorcycle Sound, expressed by its Motorcycle Sound Working Group. The AMA
organized the National Summit on Motorcycle Sound to pull together riders and user organizations, representatives
of the motorcycle manufacturers, the aftermarket industry, racing promoters, government agencies, and others to
develop proposals regarding the increasingly controversial issue of excessive motorcycle sound.
“The J2825 test allows jurisdictions around the
nation, struggling with complaints about excessive motorcycle
sound, to set reasonable limits in accordance with the SAE standard,” said Moreland. “While the AMA supports
the establishment of the SAE J2825 standard in America’s cities, towns and communities, we will continue to
fight efforts that single out motorcycles while still permitting excessive sound from other sources, such as loud
cars and trucks, booming car stereos, poorly maintained generators, whining leaf blowers, and the like.”
The SAE J2825 standard can be downloaded on the SAE website for a fee at http://www.sae.org/technical/standards/J2825_200905.