Author Topic: Interfering silencers  (Read 1559 times)

Online RichardL

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Re: Interfering silencers
« Reply #15 on: 17.01. 2019 13:24 »
Not that I am expert on plungers, silencers, or maybe anything, but it seems to me that these silencers for an RGS (or the like) are not intended to work on a plunger, which has quite different frame geometry for supporting the rear wheel.

Richard L.

Let me rewind this comment. In the first photo, I took the silencer to be the tapered type with a straight outlet pipe. The latest photo shows the cylindrical silencer I would expect on a plunger. Apoligies for any confusion caused by mine.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Online Greybeard

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Re: Interfering silencers
« Reply #16 on: 17.01. 2019 14:49 »
Not that I am expert on plungers, silencers, or maybe anything, but it seems to me that these silencers for an RGS (or the like) are not intended to work on a plunger, which has quite different frame geometry for supporting the rear wheel.

Richard L.
The correct silencer /muffler has a tag welded on in the correct place for the stud at the bottom of the plunger assembly. I imagine that the down pipes/headers are specific for this design also.

Offline Steverat

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Re: Interfering silencers
« Reply #17 on: 17.01. 2019 16:00 »
Yes one bracket on top of each silencer at the back plus one longer bracket on each downpipe. I have twin pipes ie non-Siamese. And they are not for an RGS! Still struggling however. Here are some snaps of todays efforts. I have used the outlet end of the pipes to broach the head ports as suggested, they both go all the way in now... but still the header end refuses to push in for the full 24 mm counterbore. When its in as far as it will go (see snap) and the silencer bracket is tightened onto the lower plunger clamp bolt, the (mid-way) pipe bracket is about as close to the frame as Calais from Dover docks (see the other snap). If I take the silencer off however, the pipe tucks neatly under and the pipe bracket goes straight onto the front engine mounting stud like a lamb.


1951 BSA A10 - now returned to Germany
1972 Triumph T100R Daytona
1924 B-S SS80
1965 Triumph SH Cub
1960 AJS M18CS

Offline Steverat

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Re: Interfering silencers
« Reply #18 on: 19.01. 2019 21:13 »
Thanks for your comments by the way. Summoning up the courage to grind the headers into the ports. My hope is that if the header goes in those final ~4mm then the pipe will pivot slightly and bring the exit end down for the silencer to clear the frame at the back. If I dont then I'm stuck with trying to attach the pipe bracket to the engine mount stud across the English Channel. See photos above.

1951 BSA A10 - now returned to Germany
1972 Triumph T100R Daytona
1924 B-S SS80
1965 Triumph SH Cub
1960 AJS M18CS

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Re: Interfering silencers
« Reply #19 on: 19.01. 2019 22:59 »
As I said, I had to make spacers for the downpipe brackets

Offline Steverat

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Re: Interfering silencers
« Reply #20 on: 19.01. 2019 23:30 »
Yes Ian, I get that now. From the side, (pic #1) the assembly doesn't look too bad. Pics #2 and #3 show the locations to put the spacers. But the silencers are still pressing against the lower rear subframe tubes.

I want to get the header outlet lower in order for the silencer to clear the frame tube. Its difficult to exert sufficient force to do this. I can't bend the pipe itself, I think I have to clamp the silencer up on the header, take the silencer bracket off the plunger clamp bolt, then with the engine mounting stud out of the way, put my weight on the end of the silencer, which will put the maximum bending moment on the header where it enters the exhaust port, deforming the end of the header in the port sufficiently for the silencer to come down and stay down. I think thats what Swarfy said already, its just that I need a bit of courage to do it with all my 15 stone. To tell the truth, I'm a bit worried about the strength of the casting.   *doubt*

1951 BSA A10 - now returned to Germany
1972 Triumph T100R Daytona
1924 B-S SS80
1965 Triumph SH Cub
1960 AJS M18CS

Offline Steverat

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Re: Interfering silencers
« Reply #21 on: 20.01. 2019 06:26 »
Yes Ian, I get that now. From the side, (pic #1) the assembly doesn't look too bad. Pics #2 and #3 show the locations to put the spacers. But the silencers are still pressing against the lower rear subframe tubes.

I want to get the header outlet lower in order for the silencer to clear the frame tube. Its difficult to exert sufficient force to do this. I can't bend the pipe itself, I think I have to clamp the silencer up on the header, take the silencer bracket off the plunger clamp bolt, then with the engine mounting stud out of the way, put my weight on the end of the silencer, which will put the maximum bending moment on the header where it enters the exhaust port, deforming the end of the header in the port sufficiently for the silencer to come down and stay down. I think thats what Swarfy said already, its just that I need a bit of courage to do it with all my 15 stone. To tell the truth, I'm a bit worried about the strength of the casting.   *doubt*

Last call for your views - shall I bend it? Still worried that I may break the exhaust port out of the head. I'm off for some breakfast now, maybe I'll feel braver afterwards.

Thanks
Steve *conf*

1951 BSA A10 - now returned to Germany
1972 Triumph T100R Daytona
1924 B-S SS80
1965 Triumph SH Cub
1960 AJS M18CS

Online RichardL

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Re: Interfering silencers
« Reply #22 on: 20.01. 2019 07:19 »
Not that I am expert on plungers, silencers, or maybe anything, but it seems to me that these silencers for an RGS (or the like) are not intended to work on a plunger, which has quite different frame geometry for supporting the rear wheel.

Richard L.

Let me rewind this comment. In the first photo, I took the silencer to be the tapered type with a straight outlet pipe. The latest photo shows the cylindrical silencer I would expect on a plunger. Apoligies for any confusion caused by mine.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Online Greybeard

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Re: Interfering silencers
« Reply #23 on: 20.01. 2019 09:59 »
Here is my bike, freshly restored with exhausts from Fecked. The header pipe appears to have a smoother curve than yours, but it is difficult to judge these things. The front of the silencers are touching the frame. That is not a problem as there is no movement between them.

When I fit mine I put the header pipe in the head first, locating the long stud in the holes in their brackets, complete with spacers, leaving the nuts loose. I then fit the silencer and spring the assembly down to get the silencer bracket onto the stud on the plunger. Then I tighten the header pipe bracket nuts. My headers pipes are long and go about 6" into the silencers.

Be careful about tightening those finned cooling rings on the headers; they are very weak.

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Re: Interfering silencers
« Reply #24 on: 20.01. 2019 10:07 »
Last call for your views - shall I bend it? Still worried that I may break the exhaust port out of the head. I'm off for some breakfast now, maybe I'll feel braver afterwards.
Trying to bend the pipe does not sound good to me.  *eek*

Offline Swarfcut

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Re: Interfering silencers
« Reply #25 on: 20.01. 2019 10:08 »
Steve.....On no account attempt to bend the pipe using any part of the engine as a fulcrum. You stand a good chance of breaking something.  Your picture looks as if the exhaust pipe is pointing very slightly upwards, which makes me think the error is in the sweep of the bend in the pipes, in other words to make them fit you need a downward bend almost from the pipe mounting to make this part of the pipe run level.

   You will never bend such a pipe easily and without damage with stuff in the average household....the odd crowbar, scaffold tube, big hammer.

 Your options are to return them if unmarked, try another pipe from somewhere, or find a local exhaust fabricator or pipe manipulator who can move the pipe more to where you want with the aid of a nice big hydraulic press and mandrels. My thoughts of amending and adapting the lower mounting seemed to be the best short term fix. Looks like the curve on the pipes is too tight, and raising the port that bit higher with the cylinder base spacer is making the misalignment worse as any error is magnified by the time it reaches the end of the pipe. 

  Correct plunger silencers have a no taper along their length, and are recessed underneath to clear the raised stand feet. The silencer should also lie level, front end clear of the frame. (In an ideal world!).  Or as GB's fine example illustrates.

  Swarfy

  Additional... Shortening the port end of the pipe, assuming it is straight, by just a very small amount may be just enough to allow lowering of the back end of the pipe. It can settle further into the head, pivoting  on the lower mounting.

Offline duTch

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Re: Interfering silencers
« Reply #26 on: 20.01. 2019 11:21 »

 This is reminding me of the tribulations I had fitting my headers that were 'new' chrome "Made in England" and FU-Jack sticker on them....bought cheapish (AU$100) for a reason...as I discovered  *pull hair out*

 The top ends were both tapered in same as Trev,so had to make an expander tool to stretch those, which worked well (unlike Trev, I didn't feel I could entrust them with an exhaust shop as I don't know anyone in that game)

 Then I had to cut 30mm off the same top ends as they stuck out that much too far, but then found the bend started too close in so the finned ring doesn't sit right....and the pipes still aren't seated properly- but I don't care at the moment as after six years, they don't appear to leak and runs fine, so I just use it...but that's me  >:D

 What I found to be the problem after doing 'templates' of the headers on a sheet of ply (before final installation), and comparing that to a similar template of the old pipes (bought secondhand in the '70's so probably ridgy-didge), is- the original headers have a top bend of *I think* 3" radius and the new copies have a radius of 3,1/2", which is enough to completely F***ck everything, and combined with a different bottom radius (~9" from ~9.5" off the top of me 'ead- which I don't think is right anyway but close) made the job a headache like Steves....

 Lucky both the mounting brackets apart from totally bodge, were not close to being in the right places, so I cut those off and welded some stainless flat bar on with a separate flat angle making 'two piece brackets'. Doing that at least made it easier to sort the other crap out....I'll fix them properly one day *beer* *work*

 Of course this is of no help to Steve, except I'm feeling your pain... *pull hair out*
 
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Online RichardL

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Re: Interfering silencers
« Reply #27 on: 20.01. 2019 14:34 »

 (~9" from ~9.5" off the top of me 'ead- which I don't think is right anyway but close) *whistle*

Dutch,

The story of fitting your pipes is one of creativity, tenacity and, obviously, honesty.  ;) *smile*

Richard L.
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Online RDfella

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Re: Interfering silencers
« Reply #28 on: 20.01. 2019 16:13 »
Exhausts on the A series are notoriously finniky. I believe it's Feked who make a slightly different front pipe that they claim will fit all as a solution. The problem is that it takes probably only a couple of thousandths of an inch out at the bend to create a problem, because BSA ran their pipes so close to the frame. The LH one on my A10 touches the frame. Best bet is to tweak the pipe but, as others have said, don't use the head as a mounting point for your leverage. I usually try to find a tree with a fork in the trunk and use that. It's not as if we're doing major bending work - just a tweak. Failing that, insert something in the pipe to prevent it being crushed and mount it in a vice (with fibre jaws) to get that 'tweak'.
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Offline chaterlea25

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Re: Interfering silencers
« Reply #29 on: 20.01. 2019 18:29 »
Hi Steverat,
Adding a thicker spacer or a washer or two to the rear plunger mounting should move the silencer out from the frame
I seem to remember that while working on a plunger single, that there was a special bolt to take the silencer with a "thick head" and stud to bolt the silencer to  *????* *????*
Check the header pipe for "ovality" at the head end,  *????*

John
1961 Super Rocket
1963 RGS (ongoing)