BSA C10 C11 C12

BSA C10 C11 C12 Information Center => Technical Tips => Topic started by: Brooklands on January 07, 2013, 06:30:24 pm

Title: Free silencer with every MIG bottle.
Post by: Brooklands on January 07, 2013, 06:30:24 pm
The exhaust on my C11G is pretty scruffy and the standard rear mount somehow makes the thing look a bit droopy. I have a MIG welder and for some odd reason am reluctant to throw away the disposable gas cylinders, despite never coming up with a use for them. Until...
I cut one open (make sure the thing is empty - the valve will rattle - it's only CO2, but under high pressure) and the wall thicknes and diameter compare well with a C11 silencer. The other ingredients I needed was a short piece of pipe ( 1 1/2" internal) and a few odds & sods for baffles and bracket. I used  1 full cylinder and around 2/3rds of another. Make the cuts as straight as you can - either put a strip of tape round or use an oil filter wrench to mark a line. Now the hard bit - getting the paint off - I used one of those nylon pot scourer things in an angle grinder. Dress the welds back on the domed ends.
Taking the shorter piece, make a large hole in the end ( 3/4"), and if you want it to look pretty, drill smaller holes round it - this is the bit you'll see if you peer down the tailpipe. Tack the tail pipe tube in place (I didn't have 1 1/2" tube, so I used what I had, which was around 1 3/4" external.

Cut an addition 1" ring from the cylinder offcut, shorten it by around 3/4 inch, strip the paint, and put it part way into the short cylinder. Drill 4 holes through the cylinder wall and spot weld the ring into place - line up the split in the ring with the internal seam of the cylinder, unless you can gring the seam away. The ring does 2 things - it lets you weld the two tubes together more easily as the wall is double thickness, and also lets you mount an internal baffle.

The original silencer has 2 circular baffle plates - with a hole around 3/4" in the middle, and are split & twisted like a spring washer. I made something similar with a piece of sheet steel and welded it into the ring. Make sure the baffle is securely welded as you won't see it again once the cylinders are welded together. My second baffle is inside the front pipe - see later.

The front cylinder needs a piece of 1 1/2" bore tube cut and tacked to it to get the angles right - I nearly made the mistake of trying to run the silencer too close to the tool box - which then wouldn't have opened. Mark the end face of the cylinder to match the bore of the tube, remove the tacks, and open out a hole to match (this will be oval if you are tilting the pipe upwards).
Cut 3 slots in the tube - cut first with a hacksaw, and the double the blades to get a wider slot. Re-tack the front tube.
1 1/2" bore mild steel exhaust repair sections are vailable for under a fiver, complete with slotted ends. I was just trying to stick to the junk box as a source of materials.

Trial fit the two halves together - use a straight edge to get them right - if the join isn't even it doesn't matter as it will be filled with weld. Chamfer the front tube to improve the weld penetration, but don't carry out any final welding on the outside fittings yet.
Continued.....


Title: Re: Free silencer with every MIG bottle.
Post by: Brooklands on January 07, 2013, 06:37:51 pm
Next part was to use an old silencer tube that had come from my Enfield - this was easier than trying to fit anothe baffle within the cylinder, and would be simple enough to make up from a piece of pipe. However, you could cut the first cylinder and but a baffle in there & re-weld. The tube was welded into the front pipe.
Then a trail fit & engine run - if its too noisy, reduce the size of the hole in the internal baffle plate by welding a washer over the hole, until you get the noise to an acceptable level (ie nearly too loud).
Make up a support bracket to weld to the silencer and a pick up point on the bike- mine picked up on the redundant rear footrest mount. Make sure everything clears - ie plungers, too box etc.
Title: Re: Free silencer with every MIG bottle.
Post by: Brooklands on January 07, 2013, 06:46:55 pm
Then a quick ride with all tacked & bolted in place before  finally welding everything. The tubes weld very easily - at one point I almost thought about really going to town on the finishing and getting it all chrome plated ! However, common sense prevailed and I finished the system with 2 coats of VHT brush paint, cured in the shed by putting my hot air stripper into the pipe, before fitting the smart new clip I'd had for a while.
A blast revealed it is noisier, but I got a thumbs up from an old boy in the next village - he probably has 2 hearing aids and was pleased to hear it at all!
So total cost was peanuts, and a probably full day's work . Not for the purist, but I like the look of it and  it'll do the job!
Joe
Title: Re: Free silencer with every MIG bottle.
Post by: Brooklands on January 07, 2013, 06:49:06 pm
Sorry, duplicate photo should have showed mount - crap pic!
Joe
Title: Re: Free silencer with every MIG bottle.
Post by: martin on January 07, 2013, 06:51:37 pm
"turned out nice again" ;D.
Title: Re: Free silencer with every MIG bottle.
Post by: Brooklands on January 07, 2013, 06:52:15 pm
That's 2 duplicates _  ::)
Title: Re: Free silencer with every MIG bottle.
Post by: camman3 on January 07, 2013, 07:20:55 pm
Cracking job Joe, you'll have to go into production.....provided Pete doesn't sue you  ;)
Title: Re: Free silencer with every MIG bottle.
Post by: ianinglis on January 07, 2013, 07:34:47 pm
YUF looks pretty good to me but that old back tyre looks a bit perished ;D ;D ;D ;D ;D ;D

ian
Title: Re: Free silencer with every MIG bottle.
Post by: Brooklands on January 07, 2013, 09:05:46 pm
That's not perished Ian- it's what they call patina on the Antiques Road Show, and people pay a preminum for it- just light weathering & plenty of life left in it yet! ;D
If or when I finally change it I shall put it in one of those Humana boxes so someone in the Third World can make a number of pairs of shoes out of it - nothing gets wasted here!  ;)
Joe
Title: Re: Free silencer with every MIG bottle.
Post by: elevensies on March 15, 2019, 07:25:48 pm
such a good idea

im making 2 :) when i manage to find a second bottle
Title: Re: Free silencer with every MIG bottle.
Post by: Owen on March 16, 2019, 08:36:08 am
Nice one. I might pinch the idea and get welding anything so I get a couple of empty bottles for my 45 C10 as a new silencer would look out of place
Title: Re: Free silencer with every MIG bottle.
Post by: elevensies on March 16, 2019, 09:56:07 am
i know id never have thought such a great idea

only thing is i dont use those small bottles im on the big ones, so have to find someone who has them
Title: Re: Free silencer with every MIG bottle.
Post by: Tman on March 16, 2019, 10:55:13 am
such a good idea

im making 2 :) when i manage to find a second bottle

XS 250?
Title: Re: Free silencer with every MIG bottle.
Post by: timsdad on March 16, 2019, 12:04:03 pm
Just ask a plumber - they're the same as propane and butane bottles that are used on a hand-held soldering torch. These are non-returnable and most plumbers have empty ones laying about that they have no use for.


Ray
Title: Re: Free silencer with every MIG bottle.
Post by: Owen on March 16, 2019, 12:28:14 pm
I could see if our Estates office has any if a local wants a couple.  Maybe we could sell them to armours?
Title: Re: Free silencer with every MIG bottle.
Post by: elevensies on March 16, 2019, 05:01:25 pm
Just ask a plumber - they're the same as propane and butane bottles that are used on a hand-held soldering torch. These are non-returnable and most plumbers have empty ones laying about that they have no use for.


Ray

brill idea thank you

 didnt think about those, in fact i have one i occasionally use for heating up stubborn bolts
Title: Re: Free silencer with every MIG bottle.
Post by: elevensies on March 16, 2019, 05:03:38 pm

XS 250?

yeah i made a scrambler out of one, and want to give it better looking exhausts

Title: Re: Free silencer with every MIG bottle.
Post by: elevensies on March 23, 2019, 05:01:36 pm
ohhh im so liking this idea.
iv made one for the bushman today among all the other jobs im on with

came out, and looks fantastic

this is just after id stripped the coating it had back, so still looks a bit rough
Title: Re: Free silencer with every MIG bottle.
Post by: Cosmikdebriis on March 31, 2019, 04:46:31 pm
I made one out of an old brass fire extinguisher for my rat C12. Looks kinda nice though not entirely practical. A also used a brass fire extinguisher for the oil tank.