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Thread: How loud is 105dB or 102dB? - thinking of trackday limits

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    Should Get Out More Twigman's Avatar
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    Default How loud is 105dB or 102dB? - thinking of trackday limits

    So how far away from the sound source is the volume measured?

    At what rpm is the volume measured?

    Do they filter for a specific frequency?

    How loud is 102dB? How loud is 105dB? I mean in real world comparison terms.

    How does it compare with a pneumatic drill, a train going past or my Mrs having a hissy fit?

    Where can I get the 'volume' of my bike checked before I book a trackday?


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    Should Get Out More Danny_Two's Avatar
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    Default Re: How loud is 105dB or 102dB? - thinking of trackday limits

    You can get away with quite a bit, my old Ducati race bike with full system and Termi can passed no worries. Unless your running some serious open system you should be ok.

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    Should Get Out More Spliffyaid's Avatar
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    Default Re: How loud is 105dB or 102dB? - thinking of trackday limits

    I got a full race system Akropovic Evolution system on my ZX10 and that weighed it at about 98DB, if that helps?

    The RPM differs from il4 to a twin and the distance is about 12" or so I think on an IL4 its about 6K
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    Default Re: How loud is 105dB or 102dB? - thinking of trackday limits

    105dB is TWICE as loud as 102dB

    102 is THIS LOUD

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    Default Re: How loud is 105dB or 102dB? - thinking of trackday limits

    Quote Originally Posted by Twigman View Post
    Where can I get the 'volume' of my bike checked before I book a trackday?
    ride up and down the road outside your local nick at 2/3 throttle in 2nd gear and see if they come out. if they do, your bikes too loud

    hth

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    Should Get Out More Twigman's Avatar
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    Default Re: How loud is 105dB or 102dB? - thinking of trackday limits



    My Yoshimura is barely wider than the pipe from the headers. It has no baffle and most of the insides have gone awol - it needs a repack........

    it's LOUD...but where can I get it measured before I part with cash?

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    Should Get Out More Danny_Two's Avatar
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    Default Re: How loud is 105dB or 102dB? - thinking of trackday limits

    If you intend to do more TD's maybe worth investing in a removable baffle, pretty cheap and easy to fit and remove.
    motorcycle exhaust baffle, Motorcycle Parts Accessories, Cars, Parts Vehicles items at low prices on eBay.co.uk

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    Should Get Out More dickymint's Avatar
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    Default Re: How loud is 105dB or 102dB? - thinking of trackday limits

    Quote Originally Posted by Danny_Two View Post
    If you intend to do more TD's maybe worth investing in a removable baffle, pretty cheap and easy to fit and remove.
    motorcycle exhaust baffle, Motorcycle Parts Accessories, Cars, Parts Vehicles items at low prices on eBay.co.uk
    Failing that a red bull can and a jubilee clip will do the trick!!

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    Default Re: How loud is 105dB or 102dB? - thinking of trackday limits

    Quote Originally Posted by dickymint View Post
    Failing that a red bull can and a jubilee clip will do the trick!!
    sometimes!!

    At Assen last month we were playing dodge the coke can as they were scattered all over the track

    If you are concerned then take it along to an MSV track when there is a track day and ask them to test it for you. This will then give you chance to sort it out before you book one for yourself as there is nothing more frustrating than missing sessions you have paid for because of noise.

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    Default Re: How loud is 105dB or 102dB? - thinking of trackday limits

    How it's meansured varied from track to track as they have to follow guidelines laid down by their local authority.
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    Default Re: How loud is 105dB or 102dB? - thinking of trackday limits

    The way noise limits are applied at tracks is inconsistent to say the least.
    The testing apparatus should be about a metre away from the pipe and the engine held at an RPM suitable for the bore and stroke. [The ACU have a formula for this]. What normally happens [thank God] is that the track day organisers have to be seen to be making an effort and noise testing generally consists of somebody poking a sound meter in the bikes general direction with an instruction to 'hold it at 4000....' Most modern bikes will pass easily, even Ducatis

    105dba is quite generous [much, much louder than 102dba], most short stroke fours with rudimentary cans will pass. Big V-twins and some two strokes might struggle.
    Track day noise testing tends to be more relaxed than race day testing.

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    Should Get Out More Tomcat's Avatar
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    Default Re: How loud is 105dB or 102dB? - thinking of trackday limits

    Perhaps my experience was unusual then, as I failed a noise test at a FE/MSV day at Brands last week, running road legal Allspeed expansion chambers on a 350LC.

    The bloke told me at first to run it up to 8000rpm, which seemed a bit high but you know what they say about arguing with scrutineers. FFS the bike redlines at 8500. Naturally it was screaming and he agreed I could back it down to 6-7000. Even then he measured 104+dB using a standard hand-held meter with a long rod with a forked end to locate it the right distance from the exhaust outlet. There's no real way to put additional silencing in Allspeeds so rather than try the coke can thing and risk mullering a piston I loaded up, went home, put the standard pipes back on and got back in time for the last of the morning's sessions. Not a wasted day but not the ideal way to start either.

    I was interested to hear some of the 4-strokes that had passed the noise test earlier in the day were noticeably louder on track

    The impression I get is most 4-stroke engines will pass the noise test fairly easily, however it's worth investing in a dB killer if you have any doubt. You can always take it out later (and put it back if they pull you for it).
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    Default Re: How loud is 105dB or 102dB? - thinking of trackday limits

    Quote Originally Posted by jenny_talwartz View Post
    105dba is quite generous [much, much louder than 102dba], most short stroke fours with rudimentary cans will pass. Big V-twins and some two strokes might struggle.
    Track day noise testing tends to be more relaxed than race day testing.
    Almost exactly twice as loud in fact...

    The method of measurement is stupid anyway. Anyone who's ever driven a car or ridden a bike (or indeed operated anything that's got an I/C engine) knows that the volume is proportional to the load on the engine as well as the revs. I.e. sitting in nuetral at 6000rpm will be much quieter than riding past at wide-open-throttle doing 6000rpm..

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