Armours fishtail exhaust

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T Batnes
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Armours fishtail exhaust

Postby T Batnes » Tue Jan 21, 2020 11:32 am

I will put Armours fishtails on my upsprited 350 with a Franklin P2 cam and a 7,5:1 piston.
When I look inside, I am a little baffled by the baffle plate.
It looks restrictive. What would you do?
1) Drill away the baffle plate totally? Noise?
2) Perforate it with a 1/4" drill, to reduce it by 50%?
3) Knock it back 45 degrees with a chisel or a roundbar at the sides, where it is not spot welded to the pipe?
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Last edited by T Batnes on Wed Apr 15, 2020 8:17 am, edited 1 time in total.
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Re: Armours fishtail exhaust

Postby JohnnyBeckett » Tue Jan 21, 2020 6:47 pm

HI I Would drill holes in the plate my box has not got a plate in the bottom of my exhaust box it is straight through

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Re: Armours fishtail exhaust

Postby alan.moore » Tue Jan 21, 2020 9:59 pm

Is the fishtail bit more restrictive then the baffle which is at least 30% holes?
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Re: Armours fishtail exhaust

Postby john.whiting » Wed Jan 22, 2020 12:55 am

Cops here would pull you over and poke a rod down the muffler....if it didnt hit a stop before it went to the depth of the muffler,they would kick the bike over on its side ,and plant one boot on the tank ,and use the knee as a rest to write you out a ticket for defective exhaust,and anything else took their fancy.

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Re: Armours fishtail exhaust

Postby JohnnyBeckett » Wed Jan 22, 2020 7:12 pm

that's why i would just drill holes in the plate so a rod will not go right through :!:

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Re: Armours fishtail exhaust

Postby paul.jameson » Wed Jan 22, 2020 7:59 pm

I have fishtail silencers from the Czech boys on my Square four. These have no baffles whatsoever in them so I have fitted Armours "pepperpots" in the ends of the exhaust pipes. These "pepperpots" are very similar indeed to the baffles in your silencer. The Square goes very well indeed but it is two 250cc cylinders per exhaust as opposed to one 350cc cylinder.
Given the length of the "pepperpot" and the number and diameter of holes in it I would suspect that it has a similar total flow area to that of the exhaust pipe. Clearly, the smaller holes at right angles will hamper gas flow but to quite what extent is a good question.
I would suggest fitting the silencer as it is and seeing what performance is like. Then, one day, take the silencer off and see if performance is any better. If the cops catch you without the silencer fitted, I would suggest that the difference in performance is not enough to be worthwhile.
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T Batnes
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Re: Armours fishtail exhaust

Postby T Batnes » Wed Apr 15, 2020 8:12 am

Testing the Ariel the other week, I noticed that the power fell off in the upper part of the rpm's. Cannot go beyond 55 mph at all. That was a bit disappointing, as it could easily go 55mph as an original W/NG. Also the mid-range lacked the expected "umph" from the cam and hc piston. I also noticed that the exhaust jointing compound I used on the exhaust pipe/silencer joints had blown out of the joint, and was to be found as white dots on the clutch cover and gear box. That tells me that the back pressure is too much, even with two pipes. The exhaust pulse comes to an abrubt stop, before it has to go 90 degrees for exiting through the perforations in the pepperpot. I have now wacked the blind plate out of the way, and am waiting for the weather to clear up a bit (it has been snowing and raining for one week now), before a new test ride will tell me if it's running better (I clearly expect so). But, I have started it up, and by the sound it produces, it will get some attention from kids, old ladies and local law inforcement I believe. I have to do something about it, and a friend tipped me about an "old school trick" - fit VW Beetle exhaust end tips to the end of the Ariel exhaust pipes, and put back on the empty silencers shells to cover them. So, I have now ordered a pair of VW exhaust end tips to try this trick out. They are free flowing straight through design, and should be big enough for up to a 1600 VW four. This guy stuck a couple to his Triumph Scrambler 900, with nice results: https://www.youtube.com/watch?v=73369IxR4EA&t=94s
I ended up buying these, with 28mm inner diameter and 35mm outer diameter: https://www.ebay.com/itm/161698007039
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Re: Armours fishtail exhaust

Postby T Batnes » Wed Apr 15, 2020 9:05 am

This is how I will go ahead with the VW modification :)
VW eksos.JPG
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Re: Armours fishtail exhaust

Postby david.anderson » Thu Apr 16, 2020 5:19 am

Most of the fishtail exhausts fitted to Velocettes that I am aware of have no baffles and are not too loud. Although the velo fishtail may be bigger which helps with noise reduction. And with twin mufflers I would not really expect a noise problem with little or no baffling. Another thing that may be restricting is the opening in the fishtail itself and the opening between the fishtail and muffler body.
A muffler that I purchased a few years ago from Overlander was so restrictive that it killed the performance of a VH and caused the engine to overheat. It was however the quietest single that I had heard. A chisel shaped bar and hammer fixed that problem.
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Re: Armours fishtail exhaust

Postby nevhunter » Thu Apr 16, 2020 5:58 am

You are better to use the whole volume of the muffler as an expansion chamber and baffle at the entry to the fishtail if you do it anywhere. I've had plenty of systems that kill most of the performance by excess back pressure in a pipe, where there's still a large Pulse. Nev


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