Sound Testing
The Motorcycle Industry Council has put out a
manual "Stationary Sound Test Manual" for off-highway
motorcycles and all-terrain vehicles which has become the
standard as far as AMA is concerned. Included here is the
pertinent information regarding sound testing requirements for
District 23 off-road events. It is up to each individual rider
to know the rules and requirements PRIOR to
showing up for an event. If you have any further questions
regarding sound testing, send an
e-mail to Jay or call 763-263-5835.
**Remember, the
noise limits are not just enforced during events, there are
laws in place now for riding on both private and public lands.
Check the laws at the State and County levels before
you ride.
Make
the
RIGHT IMPRESSION
-
Let's face it, noise annoys.
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Know the sound limits where you ride.
-
Maintain your exhaust system. Remember
that noise doesn't equal horsepower. Too little exhaust
back-pressure can actually cause less power and engine
damage.
-
Keep your RPM and speed down and steady
when you're around non-riders.
-
Always use a spark arrestor. It doesn't
sacrifice power, but can save the forest from fires.
-
Protect your right to ride. Remember:
Less Sound = More
Ground
-
These are the basic rules followed by AMA
District 23 events:
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The area for sound testing must be 30' from
buildings, vans, motor homes, trailers or any other sound
reflecting surfaces.
-
Sound testing requires at least two (2)
people. One person to control the sound meter and the other
to work with the tachometer.
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Set the sound meter to 'Slow Response' and
the 'A Weighting Scale'.
-
Nobody should be within 15' of the machine
being tested other than the rider and the sound testers.
-
When testing in winds above 20 mph,
position the machine so the wind direction is parallel to
the normal direction of the vehicle, exhaust down wind.
-
The machine must be in neutral. Rider must
be on the machine with both feet on the ground (ATV riders
feet can be on the foot rests). The machine must be
vertical, stationary, and in neutral.
-
Sound meter is to be held at a 45°
angle to the exhaust centerline, parallel to the ground and
20" to the rear of the exhaust outlet at the same height as
the exhaust outlet.
-
Determine
the RPM for
make, model and year from the Motorcycle Industry Council
tables. Set vibrating tachometer to test the RPM's.
-
Hold tachometer flat on
rear fender with your index finger in the center of the
tachometer.
-
The tachometer operator
must be in a position to hold the tachometer on the rear
fender and operate the throttle simultaneously.

-
The sound meter
operator must be positioned on the same side as the
tachometer operator with their right foot positioned so that
the tachometer operator can tap the top of the sound
meter operator's foot when the target testing RPM is
attained. (yelling potentially could affect the reading)
-
When the tachometer has
reached the target RPM, the oscillating wire on the tachometer will
swing in a figure eight (8) configuration. There are some
machines, like small four-strokes, which don't vibrate much.
These machines are tested when the yellow loop (at the end
of the wire) is at its widest arc (when it is vibrating the
most). *NOTE: Some small
four-strokes have a vibration spot just off idle, this will
give a false reading.
District 23 purchased two
(2) Quest meters prior to the 2004 season. These meters are
used at each event and are calibrated several times during the
season.
Select the link below to
download an electronic (PDF) version of the Supplement to MIC
Stationary Sound Test Manual for Off-Highway Motorcycles and
ATV's.
2001-2004 Model Off-Highway Sound Test RPM Data Update
updated 06/30/2004
If you are interested in purchasing
your own AMA and Government Agency approved sound level meter
to do your own testing, go to
www.machovec.com or call
Jay
at 763-263-9835.
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