Decibels - whats the law?

[porndoguk]

whats the law?

reason i ask i had an advisory on my last mot, (exhaust to loud) and that was with a baffle on the much quieter FUEL can, since then ive gone for the shorter and louder TYGA can,

im doing a bike safe with the North Wales old bill in a fortnight, and thought id end up with a ticket, so bought a baffle on eBay, i thought id make my values into a fancy laminated A5 cert incase the old bill asks?

well tonight i bought home a Decibel meter from work.
the readings are as follows

Ambient Start dB = 45-49dB AV 47dB

Without (eBay) Baffle
Idle Slow - 1.5k RPM = 86-88dB AV 87dB
Idle Fast - 2k RPM = 95-97dB AV 96dB
Fast Race - 6k RPM = 102-106dB AV 104dB

With (eBay) Baffle
Idle Slow - 1.5k RPM = 80-83dB AV 81.5dB (-5.5dB)
Idle Fast - 2k RPM = 85-86dB AV 85.5dB (-10.5dB)
Fast Race - 6k RPM = 96-99dB AV 97.5dB (-6.5dB)

Ambient Finish dB = 45-49dB AV 47dB

i ran the bike on choke for several mins to get up to temp before using the idle screw to get a constant RPM and tested over 10secs to record HIGH/LOW Values.

[Neosophist]

how far away are you testing ?

Cadwell does an 8000rpm (for 400cc 4 cylinders) 0.5 meter behind exhuast at 45 degree angle.

they have a 105db limit...

No idea if theres an exact figure in the legislation? Never seen an MOT tester with a db meter..

[porndoguk]

0.5m at 45degree to exhaust sat on top of a bag of plaster so id didnt pick up any other vibrations from the bike or floor (solid concrete) just vibrations from the air.

[Neosophist]

well at 8000rpm I think you'd be on the limit even with the baffle in

might be a bit loud there ....

as long as it doesn't say not for road use on it, i dont know that they can do anything, but if your the only guy with a loud as fawk exhaust do you really want to be referred to as the guy with the loud exhaust?

[porndoguk]

well at 8000rpm I think you'd be on the limit even with the baffle in

might be a bit loud there ....

as long as it doesn't say not for road use on it, i dont know that they can do anything, but if your the only guy with a loud as fawk exhaust do you really want to be referred to as the guy with the loud exhaust?

no the can doesnt say that but i riveted a BSAU label on the can

[Neosophist]

Well thats one way of doing it :-)

I'll bring the ZXR round one of the days.. thats loud

[porndoguk]

Well thats one way of doing it :-)

I'll bring the ZXR round one of the days.. thats loud

yes mate anytime your always welcome, would be good to catch up, im slowly starting to get the feel for her and learning the curves etc.

ive riden 140miles to HQ today first time ive riden for so long alone! bike was great managed to get 92miles and then decided i needed a pit stop to only need £9 to top her up so i guess shes runnin good at the min.

averaged about 80mph all the way nice smooth steady ride,

[graham72]

On my last MOT they gave me an advisory for noisy exhaust, my exhaust is standard except for a Carbon Can Co carbon silencer.
It is BS stamped, legal etc etc. When I asked him why it had got an advisory, he said the only reason for the advisory was that it was not the original silencer and was slightly louder, totally ok but he had to put it down to cover his back!

Wouldnt worry too much about yours unless its stamped not for road use!

[alexwitham]

114db here

[porndoguk]

114db here

at what RPM

thats friggin loud ill give you 10 outta 10 for effort