Removing carbon

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JAM RACING
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Re: Removing carbon

Postby JAM RACING » Thu Dec 29, 2016 10:28 pm

yours is identical......how olds the bike.....mine never had that last stinger


in my language it an expansion chamber....a tortured path muffler........final exhaust and what appears to be a silencer added



Guy53
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Re: Removing carbon

Postby Guy53 » Thu Dec 29, 2016 10:48 pm

The last part ( silencer ) sure look like a TY TS part.

Guy



David Lahey
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Re: Removing carbon

Postby David Lahey » Fri Dec 30, 2016 8:32 am

The photo of the perforated tube is showing that there is no gas flow restriction, but very likely the packing will be saturated with oil (heavy and does not absorb sound), so if you want to save some weight, cut a window in the side of it and remove the old packing. While there is no packing inside, you can burn out the carbon deposits that are partially blocking the holes in the perforated tube. Then repack it with muffler wool and weld up the window.
There may be some baffling (a noise trapping maze) in the box section which does not normally cause a problem unless there is something broken inside. It would probably be worth decoking it with heat to save some weight.
The end muffler could also be repacked by cutting apart, but is so small it probably doesn't weigh much even with clogged packing, and 172s are relatively quiet without the end muffler in place.
If this was my bike, I would decoke and repack the main chamber, decoke the box, decoke the header pipe and then when the engine can be run, decide what to do with the end muffler


relax, nothing is under control

Stanm
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Re: Removing carbon

Postby Stanm » Fri Dec 30, 2016 9:14 am

Hi Again
What size window would u need to repack the main muffler??

My thought was that i would split the weld along the main chamber along the sides.
Then cut through one side to remove one side only the entire wall of the main chamber.
Then remove all the old packing.
Then stuff the entire chamber with new packing. How much and how tight is another question,

Then reweld the side back on.

David can yo please give details of your repack method. And did it improve performance?

Regards



David Lahey
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Re: Removing carbon

Postby David Lahey » Fri Dec 30, 2016 9:59 am

The ones I have done like this 172 are my Bultaco Sherpa T M49 and Cota 348. The windows I cut were the full width of the flat side of the casing, but lengthwise the windows were inside the end support plates for the perforated tubes, which is where the casings taper down.
There is nothing wrong with opening them at the seams, but I think you might have to drill out the welds that hold the support plates in position
On the M49 it made no difference to performance but it sounded nicer and was lighter
On the 348 I did the end muffler at the same time as the main section. Sad to say I could not detect any difference to the way it ran but it was lighter and quieter. One of the Montesa mufflers was packed with steel wool (the original packing)
One of them, I can't remember which, I was able to get the tube out and wrap it firmly but not tight and tie the packing in place with steel wire. I think the other one I just pushed in the packing a bit at a time, working it around the back side first. I remember thinking that some of the packing close to the welding was burning/melting as I welded it back up.
I have seen some Bultaco mufflers done with a permanent window and aluminium cover plate held on with self-tappers


relax, nothing is under control

Stanm
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Re: Removing carbon

Postby Stanm » Mon Jan 02, 2017 10:42 am

Hi David
I see what you mean with the welds for the inner. You have a point may be easier to cut several windows.
thanks



Phil 850
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Re: Removing carbon

Postby Phil 850 » Sat Jan 07, 2017 9:04 pm

Well I Burnt out the oil in the main muffler.
It's now about 160grams lighter but it is all dry inside.
Unfortunately it looks like I now have a muffler where all the insulation has had the oil burnt out but the carbon deposits have been left behind :(
If you poke the end of a scriber through the holes in the inner perforated tube you can "crunch" up the carbon, and presumably destroy the insulation packing.
I might try running it how it is before cutting it up to pack with insulation.




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