750 Roadster Exhaust Silencers

Hi all, I am currently restoring a 1972 Commando Combat, many years ago I was the proud owner of a Mk11A 850 Roadster which had been fitted with early model header pipes (no crossover pipe) and reverse cone silencers which had a small restriction washer at the silencer outlet tip, this produced a unique whistler type sound when the throttle was backed off. Just wondering if anyone knows where I may pick up a pair of these silencers.
Cheers,
Spic

Lots of great distributors. Depends where you live. Shipping can be a big expense with large items.
Clubman Racing, Commando Specialties and many others can help. Mostly sold in pairs 8)
Mike

THATS A GOOD QUESTION !

these are / were the straight thru glass pac thin wall 72 or so & earlier . With the ' MUTES ' which alledgedly gave a flat spot . But you could knock them out .

First ' noise supresion 'due to beurocrats , as the Hippies in California found the noise frightening , when theyd been smoking those funny cigarettes . :? :lol:

For the record , someone may have a gen u wine pair , and can relate the Part numbers . Dunno if theres a modern equivelent . Ive not heard one with that ' blat ' recently .

One thing , if you hold them up to the light , You Can LOOK RIGHT THRU THEM , if youre heads in the right place . And not a tiney weeny hole either . The big one goes ' Straight Thru ' . 8)
The ' Mutes ; were a short ( 2 in ) bung in the back , motorists were advised to remove , to avoid the flat spot . In England .

foreal ones .

I have a Campbells on the right side and took it to Brit Cycle who were able to match it up with one they had in stock.You could try them as these pipes give a very distinct sound on and off the gas
Craig

Is the sound more important than whether the silencers stifle the cam ? It is possible to have a quiet bike which is still very fast.

Lots of these in the market, and many a nasty imitation where only the outside bears a resemblance to the real deal. however, the internals are crucial for the correct sound and performance. More on: http://www.andover-norton.co.uk/Pirate%20Parts.htm

Toga used to do good ones (not anymore, I am afraid to say- the internals are now wrong). Campbells I gave up about 30 years ago due to their- then- VERY limited lifespan and tendency to fall apart at the mounting points.

Call it self-interest or call it experience, but my personal bikes have either vintage TOGAs or todays Andover Norton offerings on them.

The Campbells I have in use is about 30 years old funny thing it was the knockoff from Brit Cycle I had to have tig welded on a cracked seam this spring.
Craig

Take a look at these: http://www.stainlessride.com/

I think they are the most beautiful peashooters on the market. They taper straight down from the reverse cone all the way to the pipe. A little pricey, but I think you get what you pay for these days.

DLBowden said:

Take a look at these: http://www.stainlessride.com/

I think they are the most beautiful peashooters on the market. They taper straight down from the reverse cone all the way to the pipe. A little pricey, but I think you get what you pay for these days.

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They do look good but the limited warranty covers everything except the fibre glass packing that will have a limited life of a few years if you are lucky ?
Perhaps by fibre glass they really mean stainless steel wire wool ?

Who makes the pea shooters with Norton embossed into the ends of them,I have a set but one has bits of what looks like corroded steel dropping out of it when end for ended.
Typically the PO said it was a new system but it seems he was related to Pinocchio. :lol:

Time Warp said:

Who makes the pea shooters with Norton embossed into the ends of them,

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Andover Norton: http://www.andover-norton.co.uk/SI%20Ex ... sytems.htm

Acotrel pretty sure I said distinct sound, I don't remember saying loud the bike works wonderful with lots of mid range and atop end I rarely use on the street.When I mentioned Brit Cycle matched up the pipe I was referring to the internals of the pipe the exterior of the pipe is a bit different but I only see one at a time usually and no one has ever pointed out that the exhaust silencers don't match.Have a good one.

Craig

I drew what I think were the original reverse cone silencers when at NV in about early/mid 1970. The packing was something like 17 or 18 ounces of fibreglass wool. The mutes were intended to meet the soon to be introduced California regs, and were secured with a self tapping screw (yuk). At the time the CA regs were the hardest to achieve. The testing to achieve whatever the limit was, was unbelievably tedious. It involved riding up and down a prescribed route, which was marked on the ex RAF Cosford runway. Accelerating from a specific point at a given speed in a given gear to a second given speed at a second point. The riding required great patience and precision. At the time it was identified that carburettor noise was a significant contributor to the overall noise, apparently the carb noise wasn't addressed until the later airfilter was introduced.
cheers
wakeup

ZFD said:

Lots of these in the market, and many a nasty imitation where only the outside bears a resemblance to the real deal. however, the internals are crucial for the correct sound and performance. More on: http://www.andover-norton.co.uk/Pirate%20Parts.htm

Toga used to do good ones (not anymore, I am afraid to say- the internals are now wrong). Campbells I gave up about 30 years ago due to their- then- VERY limited lifespan and tendency to fall apart at the mounting points.

Call it self-interest or call it experience, but my personal bikes have either vintage TOGAs or todays Andover Norton offerings on them.

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ZFD,

From the link provided in your post above, the following information
about peashooter style mufflers is offered:

--------------------------------------------------------------------
The "Peashooter" Norton silencer.

Not a critical item one might think, and there are plenty of
offerings in the market. However, it is crucial to engine performance
to get the proper item. Andover Norton sells four different versions-
the seamless one in the picture, one with seams as on the 850s, one
with "Norton" logo and seams, and a special one with 1 1/2" (38mm)
inlet for specials and Triumphs. All of them are identical
internally.

The crucial feature are the internals. They must be absorption
dampers-. many cheap ones are labyrinth ones that you can't see
through- and, also very important, not only for sound but for
performance, it must have "flutes" in the internal through tube, not
a tube with holes. Anything but the original style internals will
decrease performance, even the production racers had the same
internals.
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Can you provide more information about the above prose, by replying
to the following?


What are absorption dampers?

Why are flutes important for performance? What performance are you
referring to? Sound dampening? Horsepower?

And "Anything but the original style internals will decrease
performance," that's a pretty broad statement. Is that just sales
hyperbole, or have you conducted some analysis you can share here?
Doesn't the Dunstall style of meagaphone, manufactured by so many
companies today, with almost identical dimensions and internal
construction as the original Dunstall mufflers, offer an alternative
to the peashooter without compromising performance? There's no
flutes in that design.

Also, I always wondered who would make a muffler with the Norton logo
stamped on the side, with the alignment being perpendicular to the
length of the muffler. I always thought that looked silly. It was
never something done on a factory bike. Campbells and Dunstalls both
had a tastefully done name stamp on the muffler, designed so the
alignment made sense when the muffler was fitted.

And lastly, for the sake of historical accuracy on this subject, I
have a friend who once owned a 1970 Roadster, and the peashooters on
that bike, which I believe were the stock mufflers, did not have
flutes, but a perforated pipe in the core. It had a wonderful sound,
being quite loud, with a good crisp bark and snarl between shifts.
Maybe someone on the board with an original 1970 S or Roadster will
chime in to shed more light on this.

I can only agree with what ZFD said about the reverse cone silencers/mufflers. Anything else but the original internal layout is likely to be bad news. I simply don't believe that all, or even any, of the aftermarket manufacturers/suppliers do the level of testing and evaluation that such things require, even any testing/evaluation. Its clearly not only sorting out the noise, its getting the performance right, the carburettion right etc etc. Then once you've got one right, that set up must be repeatable for production bikes.
cheers
wakeup

"Acotrel pretty sure I said distinct sound " Yes , indeed . No Question . None Disticter ! .


that-was-quick-t11556.html?hilit=security%20system

Surounded by tall skyscaper glass fronted things at the moment . Sets of a few thoughts , or E C H O s , if youre up on the Throttle .
The antique Megas on the Tri & P.R. in the pics in the LINK above , are music to the ear . And a saftey feature where animals are concerned .
They can HEAR you coming ( and small children ) though Std Practise to declutch & coast in the near vicinity of Horses .
Baffle std. had three rivets holding it in temporally , mandatory to replace with three meaty PK screws .
As baffles are hard to get , and harder to unsquash if left lying about .

But music to the Ears , with the thick resonant shell , durable , and dont slow it down . Unless your in town . At least the SOUNDS is effortless,
much like a rowdy harley - but youre doing 50 mph potato potato potato (( :x NO I dont get it either ) not the 10 mph & change they doo ) .
in fact it doesnt make a noise unless you ARE doing someting . The Inverse of our behemouth cousins disposition . Go Far Faster . :shock: 8) :wink:

Another Query on ' search ' has wassell std replacement , comments , and fitting recomendations etc , & on gland nuts also .

this produced a unique whistler type sound when the throttle was backed off.

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This was deeply investigated by a fella a decade+ ago on Brit Iron email list and found it had to do mainly with the way the louvers were shaped. The Whistlers had curved finger nail clipping shape while the others are straight or V shaped. Every 750 reverse cone are like cherry bomb glass packs, but some had a perforated screen in the otherwise straight though path, that got burnt out fairly soon. Also these whistlers had a constant tapper from the header not the stepped up diameter.

What are absorption dampers?

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Absorption as opposed to modern principle of various chambers the gasses have to pass through (labyrinth type). Absorption silencers you can basically look through ("straigh throughs"), whilst modern silencers use various compartments and rarely absorption materials, which are a nightmare to get through today's homologation process in that one has to guarantee none of that material can escape.

Why are flutes important for performance? What performance are you referring to? Sound dampening? Horsepower?

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Yes, horsepower. Mick Hemmings tested various systems on the market many years ago and found that the Norton originals were best for horsepower all round, with the 2in1in2 Dunstall Wondersystem giving an advantage of 1bhp at one particular engine speed but below and above less horsepower than the production silencers on two production pipes. That tallies with my experience on testbed and racetrack. Gave our family racer to THE German race exhaust speciali once to get a taylor-made, performance-improving exhaust system. The bike has two cut-and-shut standard Commando exhaust pipes going to the right, then two (shortened, for space reasons) production silencers. Went home, a couple of days later the man rang me and asked me to collect my bike. He had put the bike on the testbed and had found so many bhp and, more importantly, torque, he reckoned he could not improve on it.

And "Anything but the original style internals will decrease performance," that's a pretty broad statement. Is that just sales hyperbole, or have you conducted some analysis you can share here?

Click to expand...

See above.

Doesn't the Dunstall style of meagaphone, manufactured by so many companies today, with almost identical dimensions and internal construction as the original Dunstall mufflers, offer an alternative
to the peashooter without compromising performance? There's no flutes in that design.

Click to expand...

Again, see above. Dunstall silencers are noisy- which was their main selling point then, and is it with certain customers to date. Also, I reckon most if not all are Made in China, so price is another reason why they are so popular. Ours are made in Birmingham, so pricewise we can't compete with the Chinese products.

Also, I always wondered who would make a muffler with the Norton logo stamped on the side, with the alignment being perpendicular to the length of the muffler. I always thought that looked silly. It was
never something done on a factory bike.

Click to expand...

the way the logo is one can use the silencer left and right. These are ours, but the idea was created in the 1980s (post-production), because there was great stress with registration, police, and technical inspection authorities about the noise level of a standard Commando. This was to make life for the Norton owner easier.

Campbells and Dunstalls both had a tastefully done name stamp on the muffler, designed so the alignment made sense when the muffler was fitted.

Click to expand...

Why I should advertize Campbells I do not know- I am not Andy Warhol.

And lastly, for the sake of historical accuracy on this subject, I have a friend who once owned a 1970 Roadster, and the peashooters on that bike, which I believe were the stock mufflers, did not have
flutes, but a perforated pipe in the core. It had a wonderful sound, being quite loud, with a good crisp bark and snarl between shifts.
Maybe someone on the board with an original 1970 S or Roadster will chime in to shed more light on this.

Click to expand...

Better light can be shed from our 1971 factory drawing of 06-1978 silencer, which gives the details of the internals. Most certainly not holes, but flutes. Talking of holes against flutes, the best German Triumph tuner Joerg Winkelmann had a customer's bike in for service that had "hole" type T120 absorption silencers fitted. He found it desperately lacking in power. He put our Roadster silencers and and says it felt like a totally different motorcycle- all of a sudden it had the power he'd been missing. Sure, it was a 750 Triumph, but then guess why many Triumphs have Norton Roadster silencers fitted?

Joe/Andover Norton

My Seeley 850 is fitted with a two into one exhaust and aluminium absortption muffler. The crossectional area of the tail pipe matches the sum of the areas of the header pipe's. I've advanced the cam to compensate for the pipe. From experience, advancing the exhaust opening point on a bike with two separate pipes makes the sound louder and the bike slower if you go too far. My bike pulls like a train, however it is very loud. You couldn't use the setup on a street bike, however it does work. Usually two into one exhausts are quieter than separate pipes. I will be home in a couple of days and I will start the bike on camera so you can see what I mean.

I have what I think is my original 'S' silencers off an April '69 production date. There is a baffle near the rear of the silencer, around where the widest part is, the tube that goes into the front if it goes in about 12" and ends, and then I see flutes that appear to be attached to the outside wall pointing towards the front. The flutes may be attached to another tube inside the outer shell, it's hard to tell. Here's the baffle.



and here http://i251.photobucket.com/albums/gg28 ... ermute.jpg if interested.

I'll see if I can get a picture of the front tube and flutes, but I'm going to have to rig up a light to put in there.

As I remember they sounded somewhat loud, but better than the Wassal ones I have now that have a straight through tube with flutes in it, especially at running speed. The Wassal ones sound a bit raspy at 3-4000 rpm to me.

I have someone else checking on their 'S' silencers too.

Dave

As opposed to the standard Roadster silencer 06-1978, the first drawing for 06-1312 "S"-type silencers indeed shows the rear baffle you refer to. It baffles me!
We currently make the 06-1312 inside the same as the 06-1978, which obviously came later (06-1312 first drawn 12th December, 1968, 06-1978 drawn 23rd April, 1971).

Why they did that on the "S" originally I will try to find out.
Joe/Andover Norton.