FZ6 Exhaust Sound Level

[bd43]

So, based on the lack of information pertaining to the level of sound that the FZ6 stock muffler produces to use as a baseline for comparison sake to that of slip-ons, I decided to conduct my own experiment on the level of sound that they can produce.

After some research into the subject, it was determined the adopted sound measurement procedure for motorcycles is the SAE J1287 Jul 1998. I setup the test as shown on page 3 of the document. See dp_setup_1.JPG for setup. The best ambient noise I could get was 35dBa’s with 10kph winds out of the north, 25°C and humidity at 31%. I don’t know if all this weather conditions makes any difference but since I have the data, I threw them in here.

Instead of taking a set of measurements at the prescribed RPM, I decided to take measurements from idle (1200rpm), 2000, 4000, 6000, and 8000 RPM, twice to determine an average. See dp_FZ6_Stock.pdf for results.

I then plugged the sound meter into the laptop to gather live data and record the sound with my PDA to benchmark the original sound graphically and audibly. See dp_setup_2.JPG and dp_setup_stock.wav respectively.

So what does the data say about the sound level of the Stock FZ6? According to the J1287, equation A1, engine speed is calculated to be 6857 RPM, stroke = 1.75” (from page 2.2 of the Service Manual) or if using equation A2, calculated speed would be 5600 RPM. Using the “racing” formula, from the graph portion of dp_FZ6_Stock.pdf, the stock muffler would then be rated at 90dBA. That’s my final number.

Now that I have a baseline, I will be installing the Two-Bro exhaust and see how they compare with and without the dB killers.

I hope someone found this information useful.

[Admin]

excellent!!..... I look forward to see the results.......

[Keits]

Originally Posted by biker_dude43

the stock muffler would then be rated at 90dBA. That’s my final number.



I hope someone found this information useful.

GRRR!!! My town just legislated a 100 db noise ordinance for any vehicle's exhaust and will start writing tickets at 105 db and up. Apparently they picked 100db's because the Harley's the town uses in its MC unit are putting out 97 db. If my factory exhaust is putting out 90 db then my Leo's with no db killers are gonna be way over

[Scott64a]

Originally Posted by Keits

GRRR!!! My town just legislated a 100 db noise ordinance for any vehicle's exhaust and will start writing tickets at 105 db and up. Apparently they picked 100db's because the Harley's the town uses in its MC unit are putting out 97 db. If my factory exhaust is putting out 90 db then my Leo's with no db killers are gonna be way over

There are those socialists again, MAKING you comply for the common good.

Pigs.

[FZ6inNH]

I love these threads! Thanks BD! Love the research aspect!

[Hellgate]

Originally Posted by Keits

GRRR!!! My town just legislated a 100 db noise ordinance for any vehicle's exhaust and will start writing tickets at 105 db and up. Apparently they picked 100db's because the Harley's the town uses in its MC unit are putting out 97 db. If my factory exhaust is putting out 90 db then my Leo's with no db killers are gonna be way over

Your probably fine, 105 is very loud.

[reiobard]

Originally Posted by Keits

GRRR!!! My town just legislated a 100 db noise ordinance for any vehicle's exhaust and will start writing tickets at 105 db and up. Apparently they picked 100db's because the Harley's the town uses in its MC unit are putting out 97 db. If my factory exhaust is putting out 90 db then my Leo's with no db killers are gonna be way over

Well, 2 things... 1 if they passed the law after you got the exhaust then you "should" be grandfathered. 2nd, the stock pipes are 90DB's at a very high RPM, so just as long as you are not riding around at the top RPM's then you should not cross 105db even with your afterarkets, plus it will be next to impossible to prove how loud it is.

[mdr]

Originally Posted by reiobard

Well, 2 things... 1 if they passed the law after you got the exhaust then you "should" be grandfathered. 2nd, the stock pipes are 90DB's at a very high RPM, so just as long as you are not riding around at the top RPM's then you should not cross 105db even with your afterarkets, plus it will be next to impossible to prove how loud it is.

Grandfathered? Don't think so. They're going to expect you to change. Ever try to beat a seat-belt ticket with the excuse that they didn't have that law when you were born?

I agree with your second part about the lower RPM making it quieter, but there really are very portable db meters that make it easy to check how loud the pipes are. Good ones that will stand up in court are not cheap, but the city can probably pay for them in a few days with the profits from the first 50 or so fines. People kinda thought it would be tough to test for EPA pollution violations until cheap tailpipe sniffers started turning up in every safety inspection station in New Mexico...

[bd43]

I’ve been riding with the Two Brothers exhaust on the bike now for a week or so. The sound, especially at idle is a little intimidating when I leave for work in the morning. Is it loud? I think it’s more of a self conscious thing to say that it is, knowing that I am probably disturbing the neighbors.

Anyway, I was waiting for my Two Bro P1 tips to come in (replacing the P1R’s that did not appear to kill 3dBA of noise) before I did the remainder of the TB testing, but instead prototyped my own tip for testing instead.

Here are the results. What’s interesting to note is the sound suppression of the prototypes at idle make a greater difference in sound level than at the higher RPM’s. This kind of turned into an unintentional desired effect. I can squeak out of the neighborhood at the lower RPM’s and take it up while cruising at 60kph on the streets with slightly lower than sans restrictor exhaust. The restrictors might have filtered out some of the lower sound frequencies so the overall tone might be slightly different but difficult to tell even on the wav files.

I plugged the sound meter into the laptop to gather live data and record the sound with my PDA to benchmark the sounds graphically and audibly again. dp_setup_2.JPG and dp_setup_TB_w_restrictor.wav is with the restrictors installed while the dp_setup_3.JPG and dp_setup_TB_wo_restrictor.wav is without the restrictors installed.

I’ve also included a graph that plots all three findings, stock exhaust vs. TB’s with and TB’s without restrictors. Again, based on the 6857 RPM, TB’s with no dB killers is rated at 102.5dBA while with 1” restrictors rated at 99.8 dBA’s.

[bd43]

Here is the chart that plots all three findings.