Decibels

[firko]

I have just recieved the following email from Ross Martin, the Commissions and Committees manager at MA and 'ROSMAR' on this forum. As we have previously noted, it seems that our lobbying for the 96db limit has been unsuccessful. Like it or not, it's now up to us to make sure our bikes conform to the 96db limit. I think the sound monitor guy will be working overtime at CD5.

Mark,

The Board of MA has discussed this subject and has made the following ruling:

 Issue
 Recommended action
 Decision
 
Item for decision: Noise limits for Classic Motocross
 The Classic Motocross Commission asked the MA Board to reinstate the 102dbA sound limit for CMX while the Commission investigation regarding noise is underway.
 Following consideration of the documents supplied the Board decided that the sound limit of 96dbA applies to CMX. The Board recommended that the noise tolerances for testing be noted in the letter to be sent advising of the Board’s decision.
 Thanks,
          Ross Martin

Commissions & Committees Manager

Motorcycling Australia

03 9684 0504

0416 132 150

[email protected]

 

[Freakshow]

Noise tolerance ? or is that max level with no tolerance / - elaborate please ?

[211kawasaki]

Graeme,
dont butcher the pipe, there are other ways to start to reduce noise and in the short term I feel that we need to make small steps in getting somewhere close to 96db.

Can I suggest that some rubber blocks out of a TS125 for the fins and see what happens, it does make a difference, you will find that the RM muffler will be out of packing and its a real easy job to cut it and re-pack. I was really suprised what a difference re-packing the std TM125 muffler did with no diff to the power.

I think we need to start to make the changes, and at least be seen to take it seriously.

211

[firko]

Right on Dave....As much as I disagree with the 96db limit, it's in now and we have to learn to live with it. It'll be advantageous to our sport if we are seen as a group to be trying to conform to the new limits. If we adopt the stroppy attitude of defying the 96db limit we run a strong risk of MA implementing another even harsher limit in the future. That's not a cop out, it's a reality.

[Nathan S]

Nathan, Nathan, Nathan. Things have been going along so agreeably and then you come along and ruin it all with a silly statement.   The following ......."How about looking at things in more general terms: More MX tracks are near houses than road race circuits. The road race circuits usually have far more significant/effective noise-abatement measures".......indicates that you may need to visit a few more venues. Eastern Creek is in the middle of suburbia, Oran Park is very close to Harrington Park and Cobbity rural communities, Calder is surrounded by suburban sprawl and many other road race circuits live within a cooee of housing. On the other hand, the tracks that Oldy mentioned, Ravrenswood is in a rural setting miles from housing, Barrabool is also miles from housing and on the NSW scene Clarence is miles from Lithgow and housing, Rockley is in Bum F#*K, Nowhere (Sorry Ribbo), Barleigh Ranch is miles rom the nearest house and Crawford River is also in a remote rural setting. Noise abatement isn't a major issue at those venues yet but it would be easily handled if implemented as at the road circuits. There is no reason that 102 db would be a problem at those circuits
 
 
 

Firko, Firko, Firko,

C'mon, you can do a lot better than that....
My point was (and still is) that on the whole, road race circuits typically make an effort to minimise noise, MX tracks do not.
Of the three road circuits in NSW, only Wakefield Park (which is plonked in the middle of a sheep paddock, beyond the outskirts of a country town) doesn't have significant noise abatement measures in place.

My current take on it all:
1. The rise of modern 4-stroke MX bikes has brought the noise issue back to the forefront.
2. MA realises that something needs to be done.
3. MA also realises that they need to be seen to be doing things.
4. VMX has been swept up in it all, at least on paper.

We can argue the relevance of modern noise limits to VMX until we're blue in the face, but it isn't getting us anywhere. However, if we can be seen to be doing something, then we'll have a lot more leverage (as 211 just alluded).

[gorby]

I think we all know the difference between a muffler that has been repacked and one that has blown all the packing out or carboned up all the perforations in the stinger tube.

If any one has made a proper effort to repack their muffler they shouldn't have too much problem.

The early twostrokes with only a stinger pipe will need a lightweight muffler? and the fourstrokes can be usually toned down with a bit of work.

To turn up at a racemeeting without any muffler or one that is obviously innefficient is not going to help our cause.
We all need to be at least trying to reduce our db.

[Rosco400]

Just listened to a brand new CRF250X honda measured at 93db at 4800 rpm, ....................................... now,think of the loudest fart you have done, 1/2 it and that would be pretty close, we will be getting some rude shocks/reality checks at testing

[Tim754]

Done just went out and slipped a Ford muffler over the 60mm collector box on the four into one headers. OK it used to have a curved droupie tail piece but other than that it was straight out otherwise.  But would have passed at 4000 rpm any way It looks poxy!!!!!!!!!!!!

[yzhilly]

Hey Tim have ya got one to Fit a YZF400,YZ100K,YZ80K & a CR80 .  I've been politely informed my bikes wont run at the next  cross country without some muffler work . So i'm goin to make some diffusers to point to the ground . I've already repacked 2 of them and they didnt pass. THE YZF400 with a stock muffler repacked and the YZ80 with a large aftermarket repacked still didnt pass.?

[mxmaniac]

Hello, apologies if this question has been answered in prior replys!
 I was just wondering if you have repacked your current muffler as best as possible.. travel to Tassie Aus VMX titles at a large cost... your bike is over the limit.. do u get sent home? Cant ride or otherwise?
Any correct answers to this by any chance? My dad asked me to post this question to know whether to book a ticket over!!
Any help would be great, cheers

[Tim754]

Hilly down to your local car wreckers ,piles of shitty huge ugly pong boxes! You might even score a semi rooted catalytic converter to help clean up the forking stinking ozone layer too!!! Stick the bastards on with fresh mud as neatly as you can but make sure your brace them with crud rusty fence wire taken from your favourite race track, as they won't need it much longer cos they are all high on the list of filthy earth destroying petrol head places that have to go!
 No worries about forking well bringing 100,000+ mostly illiterate people to our country every year. So what if there is not enough water,sewage ,power supply ,waste disposal, LAND ,food ,jobs , health ,public transport ,roads etc. lets fill up the place and all the space so we stop all those arseholes that like to have pleasure with machinery!!! those disgusting noisy ungreen non21st century creeps having fun! How dare they!!!!!  Tim754

[yzhilly]

Hah just settle big fella . I picked up a muffler for my YZF400 its a stock WR450 muffler and is as long as my back mudgaurd ,i havent fitted it yet but if i want to ride at this event it's gonna have to go on. I'm dont know what to fit to the YZ100 as the stock muffler wont pass eeven if i repack it . The YZ80 muffler is 12" x 3" twice the size of the stock one and it didnt pass .

[Tim754]

 Hilly I do not have the answer. You have done what I would have. Do try cutting the engines mechanical noise with rubber blocks but remember not to block air flow if possible. and even chain noise too. Do you have all the proper covers on the motor? not drilled or modified? Others here have offered" maybe" fixes. keep at it and tell us how you go please.(Likewise everybody Tim

[GMC]

The YZ80 muffler is 12" x 3" twice the size of the stock one and it didnt pass .

What is the core size of this muffler Hilly? If you have used something from a bigger bike to get a longer muffler it will have a bigger core size that will let more noise out even though it is longer as well as not running right because it has changed the back pressure.

The RPM that the test is done at is interesting...

up to 85cc  8000 rpm
85cc to 125cc 7000 rpm
125cc to 250cc 5000 rpm
251cc to 500cc 4500 rpm
over 500cc 4000 rpm

What would a BSA or Triumph normally rev to?
& what were these limits based on?

4500 RPM for an open class bike.
A TT500 would maybe be at 3/4 throttle where as a CRF450 would be at 1/2 or 1/3 throttle.
A CZ 360 or Maico 350 would also be at 3/4 throttle??

125cc to 250cc 5000 rpm
How high would a MX 250 rev, or an Elsinore 250? They would also be around 3/4 throttle compared to a YZF250 being around 1/2 or 1/3 throttle

And the 250 f's run with the 125's so are they measured as 125's or 250's?

So instead of chasing lower decibels for the older bikes maybe we should be pushing for the readings to be taken at a lower RPM.
This lets MA brag they have lowered the noise limits to keep the greenies happy & in effect it would make the levels more achievable for the older bikes.

[yzhilly]

Yeah geoff the inside diameter there is not much difference ,i havent measured it but i will have a go at them tonight . But wether it affects how it goes doesnt matter coz if it's not quieter when we front up next round we wont be riding .