Silencer for Series C Comet

[Black Flash]

Hi Vibrac,
the MOT tester we went to see races a Seeley G50 himself in German Historic Racing and is just restoring a Metisse Commando for a roadbike.
He really is a bike nut and quite helpful, but when I started up my Comet, he turned pale and said: this thing is more noisy than my G50 racer and as much as I love old bikes you are not going to ride this one on the road.
By German law you measure the noise over hard ground (tarmac) 1 meter behind and 45 degress sideways to the exhaust opening at exhaust height. you then have to rev the engine to half the rpm you have max Power (i.e. 3200 rpm) and snap close the throttle. with the resulting bang on snap shutting the meter went to : ERR .
Nuff said.
I had to trailer my bike home and am trying to calm the exhaust down just enough to please the guy.

In one respect it was real fun to show off, but then this grin cost me 60 € and I have to come and pay again.

Bernd

 

[Matty]

Thanks all

I don't think there was any baffle in my old Burgess- you could see right through it at the full diameter of the pipe. Perhaps the first owner had stuffed a "broom handle" through it during the two years he rode it, but I don't recall it being very noisy.

How does the spiral baffle silencer sold by VOC spares perform - is it unduly restrictive or quiet or what please. I believe however that it is steel and looks like the original though perhaps a bit expensive but might suit my requirements.

Matty

 

[Len Matthews]

This is long-running saga. Didn't the VOC Spares Co. go to great lengths to design a silencer that satisfied noise level and restriction? The Toga silencer, like the Burgess are of the absorbtion type and in time become less effective when the glass wool packing deteriorates. Some after market baffled silencers, notably those made by Campbells, are far too restrictive and often the baffle assembly breaks loose inside rendering them useless. Even worse, some were made with horrible external welds. Interestingly, there's mention in some early Spare Parts Lists of a special silencer for the Swiss market; what was that like?

 

[bmetcalf]

a special silencer for the Swiss market; what was that like?

I understand it emitted a yodeling exhaust note.

 

[Matty]

Hi Thanks again all

It seems that in Germany they worry about the noise emitted - perhaps this is also the case in UK rules, but no MOT station I have used has ever checked the noise level. During TT week in the Isle of Man there are loads of people running around on open pipes, making a hell of a noise and I have never heard of anyone being pulled up for this - but is TT/Grand Prix week after all !!

My only problem with noise, is that it is not very pleasant on long journeys and so I tend to use the noisy, impressive, straight through silencer for local shortish runs (including round the local town) and the performance reducing but now tatty quiet one for the longer runs where I tend to cruise at only about 60/65 mph.

Will decide what to buy when the situation becomes clearer, but may just buy a quiet one and swap as appropriate.

Matty

 

[davidd]

This is long-running saga. Didn't the VOC Spares Co. go to great lengths to design a silencer that satisfied noise level and restriction? The Toga silencer, like the Burgess are of the absorbtion type and in time become less effective when the glass wool packing deteriorates. Some after market baffled silencers, notably those made by Campbells, are far too restrictive and often the baffle assembly breaks loose inside rendering them useless. Even worse, some were made with horrible external welds. Interestingly, there's mention in some early Spare Parts Lists of a special silencer for the Swiss market; what was that like?

Len,

As I remember the Club silencer was designed to meet the original specefications and not any noise restrictions. I believe it was tested at John Renwick's and I believe it tested out at 99 decibels. I remember talking to John at the time about how loud it was. As a result, I decided not to purchase one. I kept an eye open for various reports on the silencer and I remeber a few that said it was too loud for their personal preference.

I like the Brooklands can and look forward to Tim's report. Carleton Palmer wanted to try a Velo silencer he has hanging on the wall of his shop, which also has some of that Brooklands design.

David

 

[Comet Rider]

Hi Matty
Both my dad and I have run VOCSC spiral baffle silencers, and they both failed at the front, where the silencer goes from the clip diameter to the large bore diameter, the metal literally failed.
We showed them to the guy that was making them at the time for the VOCSC and his opinion was that the vibes from a single was causing the material to fail, posibly to thin?

We now both run Armours absorbtion type silencers, but I am thinking of a goldie type next, as fitteds to my dads 650 Model19 Norton. This seems much quiter and doen't look to out of place.

Also see if you can contact John Emanuel who made his own variant of the spiral baffle silencer with excelent results

HTH
Neil

 

[Matty]

Thanks Neil

Is the absorbtion Armours silencer you are using the very noisy chromed steel one I bought about a couple of years ago, because when I complained about the noise they said it did not contain absorbtion material - wire wool or whatever, because this would be destroyed in the plating process. So which silencers do you have, Armours only offered me the stainless one, which presumably has spiral baffles as an alternative to their chromed steel one with no absorbtion materials.

No doubt the one John Emanuel "fettled" would make the bike go very well - it would be nice to know what he found out and what he did.

Knowing John however I should not think quietness would be the main design driver !!!

Matty

 

[Comet Rider]

Hi Matty,
It was sold as an "Absorbtion" type silencer, but as you say it just has an 'normous hole thru the middle

HTH
Neil

 

[Bill Thomas]

Hello Matty, I don't think Armours, Stainless has a spiral baffle, Cheers Bill.