SV1000 CCC cans <98db?

Oh and its 1m away at an angle of 45 degrees

[Mark_h]

Originally Posted by injury_ian

Oh and its 1m away at an angle of 45 degrees

Yep, did that


I've left the lardy Suzuki cans on and will take it for a ride tomorrow to see if it runs at all well. It was mapped for a flowing system so may have difficulties with the stock cans back on.

Also ran it with no cans on at all. Sounded fantastic!

[Ratty]

Mark

I'm sure it will be ok. Mine was measured at about 90 db with the BOS road legal cans on at either Cadwell or Oulton. They barely even bothered to read the instrument as they heard me pull up. You will be well in. I would imagine std cans will get pretty close to the floor.

Ratty

Hi, did you do trackday at darley? How was it? What group were you in? I have been considering there. I have done the Mick Boddice school there a long time ago. I remember it being narrow and very tight at hairpin. Thought it may be a bit manic with a lot of bikes trying to get round at once? I notice thier website says road legal bikes only (I do have original can somewhere), I thought it might just be full of darley club racers practicing and they don't want "outsiders"lol on their track? cheers.

Originally Posted by Mark_h

Unfortuantely I think I live at the point in UK furthest from any active race track!

Thruxton isn't exactly far from Fleet. It's under 40 miles.

[Mark_h]

Originally Posted by Whitty

Hi, did you do trackday at darley? How was it? What group were you in? I have been considering there. I have done the Mick Boddice school there a long time ago. I remember it being narrow and very tight at hairpin. Thought it may be a bit manic with a lot of bikes trying to get round at once? I notice thier website says road legal bikes only (I do have original can somewhere), I thought it might just be full of darley club racers practicing and they don't want "outsiders"lol on their track? cheers.

I'm there on 19th July. My bike club have sole use of circuit for the day so will be sensible numbers split by ability with lots of experienced track riders to show us newbies the way.

Current plan is try to get to scrutineering early with CCC cans. If fails, stick wirewool down baffles. If still fails retire to garages, swap cans for stock (about 20 mins in total) and try again. If still fails, stick wirewool into stock cans. If still fails see if I can borrow one of the advanced group riders bike while he's not riding or just spend the day taking photos of others enjoying themselves as I've now got a decent camera and a monster lens!

[Mark_h]

Originally Posted by wyrdness

Thruxton isn't exactly far from Fleet. It's under 40 miles.

Unfortunately there don't seem to be any events during July and I've now run out of time.

If Darley goes well may be a good choice for TD#2 though.

[Mr Speirs]

BTW the DB meter wants to A-weighted (DB-A) as that replicates what the human ear perceives sound at. You with probably find it drops in level by a fair bit.
Tracks will also be required to measure A-weighted.

[Supervox]

Originally Posted by Mark_h

Not looking good

According to my £20 maplin DB meter (DB-C, not DB-A if it makes any real difference) I'm putting out over 100DB at tickover and c106 at revs.

Dug out the original cans, stuck them on and even they go over 98db as soon as you pick the revs up.

Either
a) DB meter is no good
b) CCC cans are too loud and originals have been battered by a twin pulsing through
c) all of the above.

Looks like my track day may end before it begins. Don't really want to do best part of 200 miles to be told to sod off home!

To follow on from Mr S's reply & concerning your statement above - it certainly DOES make a difference. To put it simply DbA is constant noise (usually calculated over an 8hr (typical working day) period) whereas DbC is 'impulse' noise ie a single or series of loud bangs.

So, put in the context of a motorbike it'll certainly be measured using the DbA figure. Incidentally, 98DbA is actually quite a high measurement - the figure used where I work is 85DbA (135DbC) before hearing protection must be used.

[Mr Speirs]

Just to clarify Weighting in Decibel meter has nothing to do with length of noise (i.e. the 8hrs Supervox is talking about) it is merely a sort of filter which disregards certain frequencies.

A weighting starts to attenuate frequencies below 1kHz on a sliding scale. So when you get down to 100hz the meter is attenuating that frequency at -20db and therefore pretty much disregards low end frequency on SPL measurements, this is particularly useful for us V-Twin owners

The reason A weighting is used is the human ear naturally compresses low frequencies so there would be no point to measuring SPL's of low end frequency if it isn't being perceived by humans at the same level.

The difference between C weighting and A weighting is that if you had a 100Hz tone and measured that, A-weighting would show it roughly 20db quieter than C-weighting.

A weighting - Starts Attenuating below 1kHz
B Weighting - Starts Attenuating at around 500Hz
C Weighting - Is pretty much flat all the way down to 40Hz
D- Weighting - Is bonkers, Attenuates below around 80Hz and then boosts anything above 1.5kHz by 10db