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Discussion Starter · #1 ·
In Minnesota, the noise law for Motorcycles defers to the Pollution Control Agency's noise limits, which is 83 dB measured from 50 feet using the A scale with a dB meter (for motorcycles manufactured after 1975). I was curious if the Termi exhaust is actually considered noise legal where I live, without the chirping dB killer. I decided to measure the levels on the street outside my house, and also got a few strange looks from people out on walks. :)

I set up worst case scenario with the Termi pointed directly at the meter 50 feet away (most tests are from the side, which should be a bit quieter). Here are the results:

Idle: 70 dB
4000 RPM: 76 dB
6000 RPM: 78 dB
8000 RPM: 84 dB

My meter works by setting 0 to 60, 70, 80, 90, 100, 110, or 120 dB, and then it'll measure -10 to +6 dB from 0. I had 0 set to 80 dB, so the lowest it could read was 70 dB and the highest it could read was 86 dB. When I hit the fuel cut, the dB's jumped up over 86 dB. That doesn't really matter though, because for vehicle noise measurements, they don't measure red line.

So unless I am literally bouncing off the rev limiter, it's well within the PCA's noise limits. I'd consider the Termi to be a completely legal motorcycle exhaust in MN. Other states and countries will vary, but it does appear to be within the limits of most states. The distance for measurement is usually 50 feet, unless it says otherwise. Here is a list of states and their laws: Motorcycle Noise Limits

Here is a video of the meter:

 

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Science! I love it! Thanks for putting the numbers together.

Hmm, looks like as long as you have a "functioning muffler" in Wisconsin you're good. Good to know!

Reminds me of way back when I sat in the middle of the freeway between the dividers of the Harley Davidson 100th anniversary parade in Milwaukee. If there had been a noise limitation I think I would have witnessed the largest number of citations given in a US City in one day. Looked like below for several hours. I'm pretty sure I have hearing loss because of it.

 

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At least in our state when they do check which isn't often they look for the approval stamp that is usually somewhere on the exhaust or some sticker on the frame etc. I don't mind the stock exhaust personally but likely would want another one if I heard it in person.
 

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Discussion Starter · #8 ·
AnotherHobby could you mesure dB levels behind the Termi about 0,5 meters away from it?
From a half meter away (or roughly 1.6 feet measured in units of freedom*), I got the following results. Also, moving the unit 45 degrees to the side made no difference in the readings (since it's quite loud at such a close distance).

Idle: 92-94 dB (it bounces between bub-bub-bub-bub)
4000 RPM: 106 dB
6000 RPM: 110 dB
8000 RPM: 112 dB
 

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From a half meter away (or roughly 1.5 feet measured in units of freedom*), I got the following results. Also, moving the unit 45 degrees to the side made no difference in the readings (since it's quite loud at such a close distance).

Idle: 92-94 dB (it bounces between bub-bub-bub-bub)
4000 RPM: 106 dB
6000 RPM: 110 dB
8000 RPM: 112 dB
Thanks a lot!
 

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Discussion Starter · #11 ·
All very helpful, but this is just too funny!!

I've never heard that before, "units of freedom", love it.
The first time I saw that was on Jalopnik (where I also discovered the Scrambler), and I laughed my ass off — it's such a loaded line. I've been using it sparingly every since (usually only when I do a metric conversion). :)
 
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