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poor quality repop silencers


Gary Gittleson

Well Known and Active Website User
VOC Member
Timetraveller,
Do you mean that my "D" might have MK 1's despite all that's been written? I will say that my engine produces the "normal" clatter, so who knows?
Gary
 

timetraveller

Well Known and Active Website User
VOC Member
Hi Gary. It will depend upon whether you still have the original cams or not. I have never measured original Mk 3s so whether they really had quieting ramps or not I don't know. Over the years I have measured three sets of reproduction Mk 3s and there is nothing on them that could be considered a quieting ramp. It is not just the measurements of the lift that give this but even calculating the acceleration does not show anything unusual at the start and end of the lifts. What I read years ago was that they underground the base circle and then blended it into the lift over ?20 degrees but I cannot refer you to where that information is and I might be remembering incorrectly. Has anyone out there ever seen a quieting ramp on a Vin cam?
 

Bill Thomas

Well Known and Active Website User
VOC Member
Thinking logic, a straight through, will never be as quiet as a baffled silencer.
In fact it might make it run weak.
It depends how much power you want or need. Cheers. Bill
 

Normski

Well Known and Active Website User
VOC Member
I will make it a bit more easy for you Norman ?.
If you buy an Armours Stainless one and the Wife says it's too loud, I will buy it off you, You pay the postage !!.
I need one for my new Comet, But be Quick !!!, I am a bit keen at the moment, Just rebuilt and fitted the Gearbox, Just need to do the Flywheel Job. Cheers Bill.
That's a kind offer Bill but I think I'm going with chrome on this bike.
 

Normski

Well Known and Active Website User
VOC Member
I will make it a bit more easy for you Norman ?.
If you buy an Armours Stainless one and the Wife says it's too loud, I will buy it off you, You pay the postage !!.
I need one for my new Comet, But be Quick !!!, I am a bit keen at the moment, Just rebuilt and fitted the Gearbox, Just need to do the Flywheel Job. Cheers Bill.
I went to Feked today Bill but didn't get on too well, they're not really set up for counter sales and wanted me to buy before seeing the silencer (which was in store wrapped and boxed) which I didn't want to do. Would you do me a favour and take a look at the chrome ones in Armours please to see if they are likely to be free flowing when you go to buy your stainless one. I rode 180 miles today and I enjoyed the sound my old silencer makes sans baffle and the bike ran better too. I'm not in a hurry to get the new one.
 

Bill Thomas

Well Known and Active Website User
VOC Member
That's a Shame Norman, They can't do enough for me, Who did you see, Gordon or Steve ?, I think they must have been Busy.
I was in there the other day, And a Chap wanted to know how loud a new Silencer would be ??, That didn't go down well !.
180 miles !!, You are a Real Rider, In this heat !.
As I said, I think for Quiet you will need a Spiral Baffle ?.
All The Best, Bill.
 

Kiwi_Tim

Website User
VOC Member
My most recent experiences with mufflers from both feked and armours have been disappointing. I got some mufflers from feked for an a10 and they were both the wrong shape and the mounts were so wrong they couldnt be fitted and then some mufflers from armors for an a65 that were literally scrap (they did replace theirs at least) and the replacements of adequate but not good quality. So when it came to replacing a home made muffler for the shadow bought the spiral voc pipe and very pleased with it. Has a nice rasp and appears to pull better than its predecessor that was a gutted open pipe. Sadly we typically have to buy site unseen here in the colonies
 

Normski

Well Known and Active Website User
VOC Member
That's a Shame Norman, They can't do enough for me, Who did you see, Gordon or Steve ?, I think they must have been Busy.
I was in there the other day, And a Chap wanted to know how loud a new Silencer would be ??, That didn't go down well !.
180 miles !!, You are a Real Rider, In this heat !.
As I said, I think for Quiet you will need a Spiral Baffle ?.
All The Best, Bill.
After yesterday's ride without baffle I'm converted to noisy Bill! It actually only makes a pleasant burble which isn't so loud as to be offensive or tiring. It wasn't too hot yesterday and the roads and scenery were good.
 

Bill Thomas

Well Known and Active Website User
VOC Member
It must be me then , The heat is getting to me, Bit Dizzy, Just fell off the 560 !,
In the Garage !!, Silly Old Sod .

If you do Push On !, Make sure it's not running too weak, With an open Pipe,
Maybe it was too rich before ?, And it's Perfect now ??.
Have Fun, Bill.
 

Glenliman

Well Known and Active Website User
VOC Member
My OZ Rapide arrived with a very quiet and restrictive Toga fitted. Toga makes or made at least two types of silencer for a Vincent twin, open and fully baffled.
Top speed was around 80 mph. I thought, OK this is a mighty Vincent. Not impressed.
After drilling out the baffle with a 1" steel drill bit with welded extension, the bike came alive. I saw 115 on the speedo and that was in mph.
On the local dyno hill ( about 15-20% grade )
the bike had previously dropped down to 60 mph at top of hill with a 70 mph start at bottom, top gear used.
After the drilling it managed to pick up speed on the hill, going over the top at 72 mph!
A few years later I purchased one of the Spares Co. spiral baffle silencers.
I have not found it to provide the near magical power transformation some true believers claim.
If replacing a stuffed up silencer, then perhaps it would seem magical.
It gives the same performance as the crudely drilled out Toga, a 70 mph start gives 72 mph top of hill using top gear.

Glen
 

Jez Nemeth

Well Known and Active Website User
VOC Member
If Armourers still do a stainless silencer, that will fit a Comet, shape, size, bore and is open, or openish?

Then there might be a New, totally unused Chrome Armourers silencer available to one lucky interested party...Normski, this could be your lucky day! ;)
 
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Magnetoman

Well Known and Active Website User
VOC Member
For what it's worth, this week I measured two new, aftermarket Burgess-type silencers on my flow bench:

Burgess-type #1, 90.9 CFM
Burgess-type #2, 184.4 CFM

For comparison, an OEM semi-megaphone from a Clubman Gold Star flows 186.5 CFM (all measurements at a pressure of 20.4" H2O). I don' t know what either sounds like but I suspect there might be a difference. I know there would be a difference in the h.p.

Two years ago I put a new shorty silencer on my Catalina Gold Star, but initially it ran horribly. The problem was revealed when I removed the air box and saw a cloud of fuel at the inlet of the carburetor, ejected by too-much back pressure from the new silencer coupled with large valve overlap. The cloud enriched itself as it passed over the spray tube on the way out, and enriched itself even further when sucked back in. Drilling a number of holes in an internal baffle fixed the problem.

Related to this, even with the restrictive silencer the bike ran fine when the air box was off (at least when revving it on the driveway), apparently because enough fuel was able to escape from the cloud so as not to be extraordinarily rich. Before I discovered the problem and drilled the holes my wife commented that the bike didn't sound right.

The exhaust system flow does affect the h.p. but it's not a simple tradeoff of h.p. vs. decibels. The frequency spectrum matters to how annoying it is, and some do a much better job than others in killing the offending tones without restricting the flow too much.
 

vibrac

Well Known and Active Website User
VOC Member
I have a decibel meter since for racing and parading you have to be under 105Db at most circuits. (annoyingly the one just up the road is 85Db -drive by! I dont think a Firefly would pass that.
Anyway on the Flash its difficult to get a small silencer that looks unobtrusive on a two inch pipe and racing cams working on the basis that thin walls in houses let noise through, I got some 3" internal alloy tube with 1/4" wall and turned two end caps also with 1/4" walls and 2" inlets outlets and fitted a two inch perforated tube (car exhaust component part) flared at inlet to take the main pipe. This runs through the body with the 1/2" annular space filled with packing. result? heavy, but all bolted up it gives 105-6 Db and is small enough not to interfere with the paddock stand. In more enlightened surroundings (like the flywheel festival) I have an simple open pipe extension
 

Jez Nemeth

Well Known and Active Website User
VOC Member
To add to the mix and confirm - the Armourer's Chrome silencer is pretty much straight through -taken the best shot I could to show this, apologies if it looks like an entry to an abstract photo competition, but hey ho... On the B side, a big note of caution here, this exhaust is NEW and has been sitting wrapped in a dry garage for the last year, pulled it out and the chrome finish on the near side (bike side facing) has broken through in places and showing signs of pitting through the chrome along its length, terrible quality Chroming. I have a Suzuki pipe sitting close by, original 1981 and its perfectly fine & unwrapped . . . Photo 2 . . . unimpressed is an understatement :(
 

Attachments

Bill Thomas

Well Known and Active Website User
VOC Member
So it just has a baffle plate across the hole ?, They didn't have that on the Stainless ones,
Hope they still don't !.
I will go down there in the next week or two. Cheers Bill.
 

BigEd

Well Known and Active Website User
VOC Member
VOC Forum Moderator
So it just has a baffle plate across the hole ?, They didn't have that on the Stainless ones,
Hope they still don't !.
I will go down there in the next week or two. Cheers Bill.
I've got an Armour's stainless silencer on my Rapide. It is a straight through design. I bought it a few years ago but didn't fit it until last year. The quality seems pretty reasonable and it hasn't gone rusty. ;)
 

Jez Nemeth

Well Known and Active Website User
VOC Member
I'm heading for a Stainless one as intended, baffling is quite light -but certainly love to bring the state of this chrome one to their attention -quality is very poor if its doing that, a last thing Friday afternoon silencer. . .
Bill, be interested in what you find down there, heading that way myself day after the Severn Glos Rally -Windsurfing with the kids at Poole, then on to Bridport/Weymouth for a few days...so Bournemouth is on route. Might just take that chrome exhaust with me after the Rally..oh yes.
 
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