Black cap bean can modification

Geoffrey was a keen motorcyclist and rode a Norton Commando at this time. Terry had made the better choice and rode a Velocette Venom...

Back-to-back power tests were completed with Roe’s new silencer. It was found that the ‘annular discharge’ silencer gave a large boost in low speed torque. The net effect was an increase in power from 2000-4000rpm, a slight loss from 4000-5000rpm, and a gain above 5000rpm. The increase in low speed torque allowed the Norton to be fitted with a higher gear ratio, which also meant a reduction in noise due to the lower engine speed utilised during noise certification testing.

yorkshireferret.blogspot.com

Geoffrey Roe: The Annular Discharge Silencer

The following blog hopefully gives an insight into the research and development work carried out in the early 1970’s into the efficient...
yorkshireferret.blogspot.com yorkshireferret.blogspot.com
 
I found a loss of about 9 bhp at 4000-4200 rpm.
You have to pretty much replace the entire engine to gain 9 bhp. Even then that would be a peak number.
To gain 9 bhp at 4000- I don't think that is possible on my 850. Maybe removing the 850 engine and replacing it with a 1007 all Maney engine
If you are lucky enough to have factory type Black Caps fitted, you can gain 9 bhp at 4k rpm just by replacing them with open peashooters or open Black caps.

Glen
 
I know what's meant by straight through, but what does "straight through baffle system" mean??

-Knut
 
Last edited:
worntorn said:
I found a loss of about 9 bhp at 4000-4200 rpm.
You have to pretty much replace the entire engine to gain 9 bhp. Even then that would be a peak number.
To gain 9 bhp at 4000- I don't think that is possible on my 850. Maybe removing the 850 engine and replacing it with a 1007 all Maney engine
If you are lucky enough to have factory type Black Caps fitted, you can gain 9 bhp at 4k rpm just by replacing them with open peashooters or open Black caps.

Glen
Click to expand...
I dont doubt your results. The article is an interesting read, as are the comments, despite the dubious claims I quoted.
 
It's interesting that the designers felt the power loss above 4k to be so small.
Perhaps a bit of wishful thinking?

Glen
 
TD54 said:
Hi what a beautiful looking bike, would it be possible for you to post a picture of the
other side of your bike please, just want to see the rear set/brake set up.
Many thanks
John.
Click to expand...

John,
Thank you for the compliment. I'll get a picture for you tomorrow. They are Madass140 rearsets, he is a member of this forum. He makes some very nice stuff.
Pete
 
Fast Eddie said:
That is very interesting to see!

What struck me is, even without the baffles and reverse flow etc, even if you removed all of that, what you have essentially is a VERY long and quite small diameter pipe.

I’m even wondering if perhaps that is at least part of the reason for these ‘strangling‘ the performance ?

I also wonder how different they are internally from the T160 versions ?
Click to expand...
If I remember correctly I asked Mr Favill that very same question and he said after the design he had no control of the manufacture and marketing and did not know if the Triumph ones were different . I firmly believe after seeing inside the used muffler I used for the cut away display , and how the design was not adhered to, that today if the patent was strictly followed with CNC'd stainless steel internals the muffler would be exceptional .
 
jimbo said:
I firmly believe after seeing inside the used muffler I used for the cut away display , and how the design was not adhered to, that today if the patent was strictly followed with CNC'd stainless steel internals the muffler would be exceptional .
Click to expand...
I've been on the design and test engineering side of manufacturing all my professional life. I've seen cases where the designers sit in the proverbial ivory tower and when they get something that works "to spec" they toss it over the wall and it's up to the manufacturing engineers to figure out how to make it so that it's cost effective, reliable and with a repeatable process. It seems obvious to me that the silencers that were tested by the inventors were not exactly the same as what ended up in production. As you said, with today's equipment and process capabilities it could have been very different.
 
Deets55 said:
John,
Thank you for the compliment. I'll get a picture for you tomorrow. They are Madass140 rearsets, he is a member of this forum. He makes some very nice stuff.
Click to expand...
Pete
Deets55 said:
Black cap bean can modification
Click to expand...
Here you go John
 
mean gene said:
Thanks May go with RGM's Just tired of hearing "That's not original" bullshit!
Click to expand...
“What good are they if you can’t modify them?” Words I remember from a car show promoter who picked a modified vehicle from amongst many finely restored cars for the top show prize as he stood at the podium. As any hot rodder knows, American muscle cars started being modified as soon as they came off the show room floor. At many vintage shows, “Day 2” vehicles are very popular.
 
Last edited:
You must log in or register to reply here.
Back
Top