Do old bikes have noise restrictions?

[Paranoid Dave]

I'm sure there was a time when the noise restriction first came about, vehicles dated before that don't need to conform as i dont think you can back date laws like that. Just as my M600 don't have an emissions test but the new bikes will, or something like that.

So what year did it come about, or to put it another way, what plate on the reg can get away with being louder than is currently allowed.

???????????????

are you planning on knocking up a black and silver jobbie again?

[CK & AK]

1972 I think PD - but cant confirm for def, as AK is out hammering a bike about at the mo - but def 1970's

C

I'm sure someone on here can give the definitive answer to this but I think the MOT tester must deem that any replacement exhaust is no louder than the original.

This method is open to interpretation and must benefit older bikes.

A lot of MOT testers weren't even born when my '73 Kawasaki H1 was first on the road, so how can they tell that it's expansions are louder than the originals??

[Paranoid Dave]

thats what i'm thinking BH, they can have louder cans so long as thats the standard volume. All i was wondering is what year did the 75-80db rule come in.

The regs on emission controls you refer to came in as CK says at end of 1972.

In them days I am pretty sure it was 91dB but things like decibel meters were too expensive for an mot tester to buy so they usually just checked the pipes had their baffles fitted and wernt cut about too bad. We used to buy pipes called dB90's which were made by Dunstall Performance. They supposedly increased power and were just road legal. http://www.all-digital.net/gftp/muff.htm

Because decibel scales are not linear but logarithmic, 90dB sounds a hell of a lot louder than 81dB.

Originally Posted by Duncan

Because decibel scales are not linear but logarithmic, 90dB sounds a hell of a lot louder than 81dB.

Yup, a 3dB increase is double the 'loudness'..............

........i.e. if you have one monny on tickover chucking out 85dBs then add another one chucking out the same the total dB would come out at 88dB.

So 81 to 90 is: 2 times, then 2 times, then 2 times again.

Confused.........you will be!!!!!

[Capo]

Originally Posted by steviej

Yup, a 3dB increase is double the 'loudness'..............

........i.e. if you have one monny on tickover chucking out 85dBs then add another one chucking out the same the total dB would come out at 88dB.

So 81 to 90 is: 2 times, then 2 times, then 2 times again.

Confused.........you will be!!!!!

Tests with a 'sample' of humans, indicated that it took a spl increase of 10 to 11 dB before the 'sample' judged that the sound was twice as loud.

I've read this as well, 10dB equals a multiplication of 10 times (10*log(10) = 10dB).

Therefore, if they all had the same exhausts, it would take 10 Monsters to sound twice as loud as one Monster.

So 3bB being twice as loud isn't strictly true; it does take twice the power to produce a 3dB change but due to the ears response, it doesn't actually sound twice as loud.

Trust me, when using the decibel scale, every time the sound energy doubles, the measured level increases by 3dB.


I'll get me coat...................................

I agree with what you say totally - twice the power = 10*log(2) = 3bB

But the ear also has a roughly logarithmic response and as stated earlier, tests have shown that to get a perceived doubling in noise level you need 10 times the power, not twice the power.

http://hyperphysics.phy-astr.gsu.edu...060/p406i.html

Hey think how sounds travels in free air / space? it's not going in one direction / plain of travel

3db is double the orgininal value...but sound decreases to the X² power..hence the logarithmic scales.

so 3dB may be double the sound power but will not go double the distance from sound source, exhaust pipe...bring on calculator and square root values

I knew someone back in the mists of time, well late 80's in Chelmsford, Essex. Who had a Ducati Darmah ( is this correct name? ) big black and gold beast. It had "Conti" exhaust as standard. These were F'in noisey..but legal some how :twisted:

Originally Posted by Andy S

Hey think how sounds travels in free air / space? it's not going in one direction / plain of travel

3db is double the orgininal value...but sound decreases to the X² power..hence the logarithmic scales.

so 3dB may be double the sound power but will not go double the distance from sound source, exhaust pipe...bring on calculator and square root values

I knew someone back in the mists of time, well late 80's in Chelmsford, Essex. Who had a Ducati Darmah ( is this correct name? ) big balck and gold beast. It have "Conti" exhaust as standard. These were F'in noisey..but legal some how :twisted:

Darmah is indeed the correct name.....a pushrod 900 and reliable as chocolate teapot Contis were the pipe to have on your Duc or Guzzi and hold the record for the thinnest layer of chrome ever deposited by a human without nanotechnology. They were quite loud but not that bad unless the inside were totally removed which to be fair was quite often the case.......aaah its all coming back now....La Franconis were also a desired fitment and although boasted slightly better chrome the insides turned to **** within a year.....the late 70s were not a good time to own an Italian bike unless it was a Duc 350 single which to be fair was worth shagging and pokiing your eyes out with a pencil for :burnout:

ta ra

[Pedro]

Think you'll find a Darmah is a bevel motor not a pushrod....

[Paranoid Dave]

thanks for all the comments, muchos helpus. My new monkey will be pleased.