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How is exhaust sound level measured?
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Posted by: Uechi45---------------------

I have a sound meter and will be doing testing in a day or two. Please tell me the following (if anyone really knows)

1. How far from the exhaust is it measured.

2. From what direction.

3. At what throtle setting.

4. Is the meter set at the "A" or "C" weighting.

I will be testing KLX300's with various systems and an XR200 as well so if anybody knows this stuff please reply.

Posted by: NVR FNSH---------------------

1. 20 inches from the exhaust outle
2. 45 deg from centerline of the bike
3. Half of red line
4. 'A' weight (most closely represents human hearing)

Have fun,

Brian

Posted by: Uechi45---------------------

Thanks Brian. I just did some testing. Here's what I got.

1. KLX300 with stroker head pipe and Supertrapp IDS2 with 12 discs:

All measurements directly behind(unless otherwise noted)

Idle@36"=85db
1/4@36"=98db
1/4@72"=96db
1/2@72"=99db
Measurements to the sides at 90 degrees were about 1db lower

2. KLX300 with stock head pipe and muffler with baffle removed:

Idle@36"=80db
1/4@36"=92db
1/2@72"=94db
Wide open @72"=107

3. KLX300 as above but with 1" diameter turn down tip (home made)

Idle@36"=76db
1/4@36"=90db
1/2@72"=93db

All measurements taken with Radio Shack analog meter "A" weighted.

If anyone else has done similar tests please let me know.

Also, what are the limits for various events? (enduros, hare scrambles)
or just the limits that the Green Police look for. Thanks.

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How is exhaust sound level measured?

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