Author Topic: DB killers  (Read 403 times)

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AdrianS

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DB killers
« on: 13 March, 2019, 15:23:51 »
Its been a year since my B40 restoration has been completed.
However, I fitted a pattern exhaust silencer which looks fine but does anything but silence the engine. Whereas I can tolerate the noise, many people have commented how loud it is!
Has anyone fitted an aftermarket Decibel Killer - one of those small perforated pipes placed into the exhaust tail pipe?

If so, do they work? I know they are cheap but I cannot see how a 6 inch piece of perforated tubing can quieten the exhaust down!

ANDY HIGHAM

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Re: DB killers
« Reply #1 on: 13 March, 2019, 17:00:33 »
I have them in the Scorpion silencers on my ZZR1400, they do reduce the noise at the expense of some power (6 BHP or approx 3%)

MICKREEVES

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Re: DB killers
« Reply #2 on: 14 March, 2019, 07:36:17 »
Yes, I have tried several patterns of added baffles. The more restricted - less noise, less power.
I now run without the baffle. This has a benefit. coming up behind a row of cars, they must hear my C15,
and they will often pull over to the kerb to let me pass!
We live on a main road and hear the traffic go by. most cars are near silent,
but motorbikes can usually be heard. some are very noisy
 One can be heard  (in our 30 mph limit) all the way to the roundabout half a mile away.
When I rode as a lad, the police would sometimes check noisy bikes by poking a stick up the exhaust.
I think I had to explain that my silencer was an absorption type, and had no baffles.
Mick

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Re: DB killers
« Reply #3 on: 14 March, 2019, 22:22:17 »
Being a cheapskate, I cut a bit of surplus 1 cm square mesh (the kind you have on rabbit hutches) and rolled it tight and shoved it up the tailpipe of my noisy B31. Being tightly rolled, it tries to unroll and effectively wedges itself in place. It takes the edge off the exhaust racket but doesn't seem to reduce the awesome power.

ANDY HIGHAM

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Re: DB killers
« Reply #4 on: 15 March, 2019, 12:47:56 »
i have found over many years of playing,  silencer with an open chamber to fool the exhaust pipe that it has reached the atmosphere works well. after this chamber an absorbtion section gives a nice mellow sound. What I have described there is virtually a Burgess silencer

elevensies

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Re: DB killers
« Reply #5 on: 24 March, 2019, 18:09:24 »
ooo iv just made something along the lines of one of those

a old used welding bottle, a length of perforated tube that runs fill length insine and some pipe for the outside, then a couple of black silicone hoses to use as joints

work too


griffo

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Re: DB killers
« Reply #6 on: 24 March, 2019, 20:18:43 »
Being a cheapskate, I cut a bit of surplus 1 cm square mesh (the kind you have on rabbit hutches) and rolled it tight and shoved it up the tailpipe of my noisy B31. Being tightly rolled, it tries to unroll and effectively wedges itself in place. It takes the edge off the exhaust racket but doesn't seem to reduce the awesome power.

Pray tell me where have you have found a B31 with awsome power ?   Could you be comparing it to a D3 perchance ?        Griff
Safe riding saves pinch marks on the seat...

Pete C

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Re: DB killers
« Reply #7 on: 25 March, 2019, 06:31:23 »
My B31 will flay a rice pudding any day (just)  ;D

STAR TWIN

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Re: DB killers
« Reply #8 on: 25 March, 2019, 17:07:11 »
D3s are nothing. For a real challenge, I'll even take on a D7.

chaz

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Re: DB killers
« Reply #9 on: 25 March, 2019, 17:39:48 »
dont get out very often, the A7 has straight throughs, the new A50 has inserts while the  T100 has the short stubby silencers that fit on a VW Beetle, they do a good job quietening down and dont look out of place ( but more often runs without them).
 I recently had a GSXR600 in and jetting all over the place, overfuelling bad as had 1200 jets in. ran better taking the baffle out but needed dropping jet size to run with baffle.
many modern bikes rely on back pressure that the baffles provide, its normally the plate or disc that stops the noise allowing gasses to flow through the baffle holes.
as an aside we used to make gun silencers, they were a tube with straight through hole and there was a couple of dished discs inside which the noise bounces off of to quieten.
https://www.youtube.com/watch?v=7pOXunRYJIw