Noise Emissions

[fatboyracing]

Hi All,
Noise emissions from our vintage bikes is going to be very important next year after being tested at the nationals this year and failing I have looked at ways of making my bikes quieter for next years nationals. I can tell you ,you will be tested next year and some how our bikes need to be at the new readings of 96db this year it is a bit realistic at 102db. My bike has a reading at the moment at 109db and I may have to change my pipe to quieten it, I have a Peter Allen Power pipe from the 70s and it is noisy , back then noise was not a problem. I have been told that this year was a warning and next year you must comply with the GCRs. I have tested all my bikes and they all failed my best was my DT 250 at 103db and the worst was my XL 350 at 109db I don.t know how to get them down I am going to try a few things in the next months i.e repacking and rapping the pipe. Any ideas would be greatly appreciated.

Cheers
Fatboy

[Quicksilver]

Noise Emissions. Surely not. These old tarts bellowed from the day they where made, now we have to quiet them.

[caps 999]

one word packing and lots of it

[DJRacing]

How do they test the noise level? At what distance and rev range? Like a 2 stroke at idle always seems louder than a 4 stroke at idle but its a different story when ya feed them both some gas. The modern 4 strokes bark like hell and the noise carries for miles but a 2 stroke with correctly packed silencer on doesnt seem no where near as loud. I can understand you guys worring about it. I would be piss if I wasnt allowed to race because my bike was a bit loud, esspecially when some of them havnt got repackable silencers.

[Nathan S]

DJR's question about how they're tested is very important. If it's any sort of stationary test, then it will be a complete waste of time.
Rally cars are supposed to be tested before every event - there's a clearly defined, stationary test.
Problem is, even before comeptitors implement their 'work-arounds', it proves nothing - a ported rotary at 5000rpm with no load is always going to be loud, but they're relatively quiet on the road. Similarly, a turbo car running anti-lag will usually breeze through the noise test, but will make a huge racket out in the forest.
A mate has a twin-Webered 1600cc car. It's quiet. But it regularly fails the noise test because it crackles through the exhaust at 4000rpm with no load... :roll:

So the upshot is that cars are no longer being tested. Unrealistic, unrepresentative rules quickly become unenforceable.

My local (car) hillclimb track tests the cars while they're competing - every car on every run. Works well, but I've got NFI how you make that work in a race situation where there's more than one bike/car on the track at once.

[Freakshow]

YOu cant test a passing bike do to rebounds of any object or distortion in the enviroment.  any test not in a controlled enviroment is a joke to keep the officals happy.   Road races usually has a microphone at drive by level and pulls redings as they race past.   Same problem though sticking a reader on the track and praying its at zero at set up is only a guide, the allowance would need to be even greater if any MX bike was tested on a drive by due to the enviromental factors being even more uncontrollable.  THey have had a lot of issues with this in the states, due to tracks closing as the urban sprawl wanting the land, then inforcing the limits.  ill put a link up to there forums as this topic has been a great debate over there as they try to work 99db rating on Flat track harleys ?

[Lozza]

As we type the boffins in the Institue's accoustic lab have all the answers.Just a matter of 'special' packing and hole size in perforated tube I am reliably informed.One hope's the db meter is never pointed toward the rolling test bed TS 400

[pokey]

uhuh Lozza. Packing is Old  (pains me to use the word) "Tech".

 A two smoke  pipe is all about acoustics. Alll about acoustics  as The institute  well knows.

"To defeat them selves use sound waves.  Herh herh herh."

[Freakshow]

Some very good points are under 96db is near impossible, Track and sports admin need to create better absorbing features, trees, soft walls and all sorts or enviromental curves can soften the sound right down to nothing at 200m, its the niose outside the track that should be monitored, not the bikes so too speak, if a single bike is loud from 200m then it can be controlled and asked to get its DB down, but enforcing it in a drive by is futile and will kill the sport.  Track managers, MA reps and clubs need to lobby the sound levels be set to resonable levels per class as per year levels, no matter how you squeeze some things they where never meant to be squeezed, how can you have a pre 75 bike with a 2007 packed pipe it spoils the patina ?   then all sound levels should be noted per track at levels based on  where they are in relation to the enviroment / community.  WHy would you need to enforce sound levels at a track in the middle of nowhere ? or a rediculas 96 level.  maybe if it was a inner city track it could be brought right down.  but they have to get away from pushing the bikes down to far, and not looking at the fundemental factors in noice abaitment - the enviroment.  most MX have trees and shrubs, correctly placed and mounted we can cut outside noise in half.  this debate is always skewed

[Freakshow]

WOnt work - old debate and if the Pro's in the US cant do it there is no hope for a bunch lads riding old bangers, even with the institute powers, all it will do is sporn more wacky "brocky powercells" or buy now items like this  --> http://www.impulsengine.com/newproducts/negative_supercharging_emission_vapourisor_muffler.shtml



" I went to the South East Am Regionals and
>tested with my CRF 450 Pro-tec low pipe at 105 with AMA's
>meter, same brand as mine which tested 99!!! Huh? Go figure!

I can tell you why. Unless a sound meter is calibrated using ASME or CAGI guidelines BEFORE EACH USE, the readings will not be the same, therefore, can not be used in favor of or against someone. I tried to say this a few weeks ago on this forum, but was basically laughed off as a crackpot. What the AMA is trying to do (lowering sound levels at races) is a great thing, they are just going about it all wrong. The AMA is going to have to hire an Engineer that knows what the heck (s)he is doing, and train the people that are responsible of these sound tests, and train them using quality dB meters. I've said it before and I'll say it again, you CAN NOT enforce these readings using a $50 meter from Radio Shack. It takes, at a minimum, $1000 worth of equipment, and a person certified in the use of this equipment. They will have to put a person on the payroll that can travel to various races to take these readings. That, or pay to have a couple thousand people across the country certified in the use of this quality equipment. If / when the AMA decides to do this, someone please let me know. I want to apply for the job. I was trained for it using the CAGI guidlines. "
  can you see MA spending all that coin to ship certified meters and personell round the country to make a correct reading ?  NOPE - if you get refused lodge a protest and still race.   unless you racing at the island you cant tell me they will be uuble to meter you under 100db at a MX track

[Freakshow]

yep i got it here is the answer  --> 

[attachment deleted by admin]

[Freakshow]

See its the enviroment not the bikes in general ! -->

Majority of complaints we receive during racing is regarding the Public Address System more than the noise from the race vehicles.

At one track we can race up to 8pm, we can start as early as 7am, however we cannot make any announcements over the PA after 6pm in the evening. The neighbors have an agreement with track management regarding that.

Three of the Indoor Buildings we lease for races have outside speakers. We always remember to cut off the outside PA speakers before 9pm to keep the neighbors from complaining. Never had a complaint about the noise from the engines, just from the PA system.



Attend the 5th Annual AMP Outlaw Winter Nationals
Oct-April 2007-2008
OK Corral Indoor Arena

[husky61]

Acoustic reduction = attenuation

As we are all we aware , Maximum engine performance requires minimum pressure drop though the acoustic reduction device or silencer.The required Acoustic performance as stated in the previous posts  can be easily achieved though silencer design whilst maintaining minimum pressure drop and retaining the required performance . The issue faced with such silencer design is overall  size ,  ie weight and length of the required device . They certainly will not look pretty , but they sure will be effective.
Now having said that , if you have a noise meter of reasonable quality (and it must be of reasonable quality and suitably calibrated),that is used by a person not suitably trained in the use of such a device(and i doubt that any of the individuals using said devices will be trained acoustic engineers capable of interpreting the readings taken) the data or reading will be highly questionable.
Take into account the evironmental variables including the variations in background acoustics at any given location where such measurements are taken ,as stated in previously , the acoustic measurements will be highly questionable to say the least.

[Nathan S]

... all sound levels should be noted per track at levels based on  where they are in relation to the enviroment / community.  WHy would you need to enforce sound levels at a track in the middle of nowhere ? or a rediculas 96 level.  maybe if it was a inner city track it could be brought right down.  but they have to get away from pushing the bikes down to far, and not looking at the fundemental factors in noice abaitment - the enviroment.  most MX have trees and shrubs, correctly placed and mounted we can cut outside noise in half.  this debate is always skewed

Hey, good post!
The maximum meter reading that's enforced means nothing in itself. The only thing that really matters is if it pisses off the nearby residents.

Other thing worth mentioning is that think the meter should be calibrated in the dB-A scale, but they never seem to be.

[DJRacing]

Freaky and Nathan, you 2 have it right I reckon. Its not the noise at the track. Lets face it, we as riders like the sound of motorbikes and I would say that most of the spectators at meeting are the same. So really its the near by neighbors that are the problem. There should be a db reading outside the track at a certain distance. But in saying that how do you know which bike/s are the noisey ones. If it is only in certain races then you are narrowing down the culprit, and lets face it as riders we generally know which bikes are noiseier than others. As Freaky has already said, if they (officals) cant get a true or standardize reading, then as riders you wouldnt want to accept being not allowed to ride esspecially if the next bike was the same and it was allowed to race.

I surpose we are lucky over here (at the moment, but it is coming) because the only thing at the meetings that has DB on it is the BEER, and we like lots