Homemade carbon fiber silencer

Mike P.
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Edited Date/Time 12/24/2015 2:29pm
Hey everyone, before anyone gets to excited let me start by saying that unless you are building a garage queen then I do not recommend investing time and money into a carbon fiber silencer and let me explain why. I have made a couple (I am not machinist or fabricator), but the first one I made was for my 1980 RM125 (see the photos below), which I have rode with and it’s holding up pretty good (though I don’t ride this bike much). Back in the day American Suzuki’s MX race team used them (guys like Hannah & Cooper), however I do not believe they used them for their strength rather they were used to save weight. Carbon fiber in the form of a silencer is strong, but it will break. US Suzuki riveted theirs together, which if I had to guess, they did it for two reasons, one for weight saving and two because what’s the point in taking the time to bolt it together when it might be broken in one moto (and they easily had spares handy). Have you ever tried removing a rivet..? Yeah, you would tear the hell out of the carbon fiber doing it. In Europe from all the photos I have seen of the factory RA Suzuki’s on Donny Schmidt appears to have used a carbon fiber silencer and I think the reason was that in Europe they were not held by the production rule that we were held to in the US so they had works swingarms and other such lightweight parts (other ways to make the bike lighter). So why risk smashing a carbon silencer…they just used aluminum.
When I first made the silencer for my 1990 RM125, I used an acerbic carbon silencer (do not remember what it came off of), which was too wide (I think it was for a 4 stroke), so I cut it in half to make it narrower (see the photos). My plan was to re-fiberglass it, but I have since ordered another oval tube which I will try and make work when it arrives in the mail. But check out the photos below as my silencer will be very close to the factory silencer. I’ll keep you all posted as I build it.

Mike











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wpark89
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12/19/2014 5:58am Edited Date/Time 12/19/2014 6:03am
Cool.

I have retro fitted several silencers for some of my restoration projects. I used an old Acerbis carbon Fiber silencer for my '88 Cagiva 250 and it looks really trick. I found it on craigslist for 25 bucks locally and I think it was off a mid 90's KTM 250/300. They had the funky curved stinger tip on the end but I just cut it off straight. The way most of the carbon silencers mount with the adjustable clamp make them pretty simple to fit.

I think the price is outrageous for that new one PC is selling and you can find round carbon fiber tube cheap online. But where did you find the oval?

I'm interested because I used a stock silencer I had laying around from my '92 RM 125 on my '95 KTM 125 project a few years ago and it was a pretty easy job....I assume the '90 one your building is close to the '92 so I should be able to use the same parts to build one for the KTM.



Frog #1
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12/19/2014 2:24pm
Love that Cagiva! Know of any for-sale?
wpark89
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12/19/2014 4:16pm
I havent seen any lately. Guys are hording them. Usually a really rough one will pop up on craigslist every couple weeks somewhere around the country.
lostboy819
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12/19/2014 6:12pm
wpark89 wrote:
I havent seen any lately. Guys are hording them. Usually a really rough one will pop up on craigslist every couple weeks somewhere around the country.
Yes they are, I bought a bunch of the carbon fiber Answer silencers back when they were blowing them out for $25.00 each from Tucker Rocky or Parts unlimited. I just cut off the tube that has the bends and weld on the correct one and I have a carbon fiber silencer. I also have several of the acerbic ones still in the package, I have used them on my YZ167 and snowmobiles and shifter karts. I love carbon fiber.











1

The Shop

Mike P.
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12/19/2014 7:25pm
WPARK88,

I bought the oval silencer on ebay and have no idea what bike it came off of. Acerbis made it so I would check with them.

Mike
rmartin517
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Dickinson, TX US
12/20/2014 7:16pm
This is my answer silencer. I did the same thing. I cut it and welded the correct mating pipe.




12/20/2014 10:20pm
Anybody have a link to some oval or round carbon tubing suitable for a kx250 silencer? I've got sheets of fiber coming but it'll save time if it's already formed into a tube.
Mike P.
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Chantilly, VA US
12/22/2014 5:33pm
Aceofspades,

I ordered an oval carbon tube from a company in England, but it has not arrived. Once it does (and I have it in hand i will update you).
Mike P.
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12/22/2014 5:42pm
Okay, I found a pretty roached out 91 RM125 silencer (i couldn't bear the thought of cutting up one of my two silencers as they are in like new condition) and I cut about an inch out of it (see below). I did this because the works silencer Suzuki used was about an inch shorter than the OEM silencer. I plan to also cut the mount from the aluminum part of the silencer (I plan to rivet the hanger portion to the carbon fiber tube and that will be my silencer mount to the frame.



12/22/2014 9:23pm
Mike P. wrote:
Aceofspades, I ordered an oval carbon tube from a company in England, but it has not arrived. Once it does (and I have it in hand...
Aceofspades,

I ordered an oval carbon tube from a company in England, but it has not arrived. Once it does (and I have it in hand i will update you).
Thanks!
Mike P.
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12/25/2014 12:30pm
Merry Christmas to everyone! So on this joyous day, I stole about an hour to run down to the shop and do some more work on the carbon fiber silencer. Today I shorten it (now it look more like the factory silencer Cooper & Schmidt used). I also attempted to cut the hanger mount out of the standard aluminum silencer tube and ended up damaging it beyond repair (I was using the wrong blade in the cutter...silly me). Anyway, I will just have to fabricate one out of aluminum. More to come!









Mike P.
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12/26/2014 11:47am
Okay, I just fabricated the silencer hanger and drilled holes for stinger and end cap (see photos). All that is left is the clean up (painting and sealing the fiberglass)!







Mike P.
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12/27/2014 9:32am
Last night I put on the first layer of carbon fiber and I removed the wrap today and started sanding. Sanding is perhaps the worst part of this task. Once sanded I had to apply another sheet of CF and I used the hardener to seal the inside of the tube (I had to cut the tube in half to make it fit correctly). Between the two sheets of CF on the outside and the hardener on the inside this tube will be plenty strong. Once I am done with the sanding I will polish the tube. Now to the cleaning up the stinger, end cap and the hanger. More to come, Mike.









Mike P.
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12/28/2014 2:02pm
Here's the finished product (although I still have to seal the ends with clear permatex). Here's what I learned and want to pass on, I am not a fabricator or machinist (just a guy with a passion that likes to figure things out). That said, if you plan on making one, first try and find an oval tube and if you have to cut it in half, wrap the entire tube in carbon fiber (I only wrapped where I cut the tubes in half and even after all my sanding, up close you can still see the differences in the CF). Also, make sure you align you holes should you decide to drill extra holes for bolts (it will look a lot cleaner that way). All in all, if I were not building this Guy Cooper tribute bike I would not waste my time with CF silencer because while it is a little lighter, it is not so light that it is worth the headache, and while CF is strong, the aluminum silencer is better long term if you plan to ride with it. Mike















Mike P.
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1/19/2015 4:34pm
New oval tube arrived in the mail today from the UK and after getting a carbon sliver in my pinky, the tube worked flawless with the stock stinger/end cap (i just had to work it on at each end). And the best part is that the tube while more than $120.00 with shipping arrived with enough for me to make two silencers (check out the photos). However, I do want to caution you, this particular carbon fiber is really thin and I personally would not ride with it. The first tube I made is way stronger and not much heavier, so I will ride with the tube I made and use the new one for photo ops. Mike















Mike P.
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12/22/2015 7:00pm Edited Date/Time 12/22/2015 7:59pm
It's been a while since I posted and for some reason I decided to make a third carbon fiber silencer (It's the one mounted on the bike in the below photos). This silencer is a bit different and way lighter (to the point I probably wouldn't race with it). The factories likely riveted these silencers together because when they got smashed there's really no point in trying to rebuild (you just put another one on). I would however race with the other two as they are thicker (at a cost of weight but still lighter than stock). After I made the carbon fiber chain guide, I kept looking at my silencers and while they work, I wanted something more like the factory silencer and this last one is pretty close (not 100% but close). I haven't weighed it, but it is stupid light (is the best phrase that comes to mind).













wolfy0067
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Wernersville, PA US
12/23/2015 5:22am
This is pretty cool, I need to make one myself, Mike P looks cool, you need to clean up the mounts, file the edges and rounding them off I think would really finish your project.

Respectfully, Wolfy

vmx3
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Indianapolis, IN US
12/23/2015 6:36am
Frog #1 wrote:
Love that Cagiva! Know of any for-sale?
Brian at Team Cagiva in SoCal has a bunch that he is selling, he has good runners, good resto projects and some basket cases.
Mike P.
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12/23/2015 4:50pm
Woofy,

I took your advice and I cleaned up the bracket a bit (see below photos) and I cut the carbon tube (shortened it), which I had planned to do as the works silencers were a bit shorter than the stocker. However, I won’t make the silencer look perfect as I want that “works” handmade look that came from the factory. I took a couple of photos of some works parts to emphasize what I mean. Starting with the below photo of Ricky Carmichael’s last RM250, which had a hand built carbon silencer by Pro Circuit, and if you look at the photo below that one, you will see the Answer Racing carbon silencer on my 98 RM250 that while trick looks mass-produced next to Carmichaels. Another example is the works swingarm on my RM125 in the below photo that has the welding running straight down the middle of the arm, which unlike the stocker that had a smooth production line built look to it. I think that factories have lost the art of making handmade works parts, don’t get me wrong, they still make some pretty trick stuff, but just about anybody with a couple extra grand in their pocket can duplicate the look of a modern works bike (but not internally). I also think that the cost to make handmade parts is another reason they don't make them so much anymore along with the fact that there are many aftermarket companies capable of doing the work so the factories often use their parts or commission them to make them. Back in the day you couldn’t come close to making your bike look like a works bike as most of the parts were machined and sometimes crudely (take a look at the below photo of the works Honda HRC swingarm). The left side of those arms almost looked like art, but the chain side looked like someone in a welding class took a torch to it. Anyway, I just like the “one-off look” is all I’m saying, cheers, Mike














wolfy0067
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12/23/2015 5:57pm
Looks beautiful, Mikey u got some trick stuff keep it going
Mike P.
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12/24/2015 2:29pm
Merry Christmas everyone! It was almost a year to today that I was in my shop on or after Christmas building my first carbon silencer and just yesterday I made a major blunder on my latest silencer as I misaligned the end cap holes in the carbon tube on the outer side of the silencer. I tried to correct it by drilling a 4th hole, but due to poor lighting I made a bad situation worse (see below). I was going to scrap this tube and start again when I came up with another idea…I took a thin piece of alloy that I heated with a torch and carefully shaped it into a band around the end cap. I next drilled out the rivets in the end cap and filled the holes with permetex and then I wrapped the band around the outer cap. Next I re-drilled the holes in the end cap/rear carbon tube and whala…the finished product is below weighing in at 421g. Now, I don’t know if that is light in terms of carbon silencers, but it seems way light to me (you’d have to ask Phil Denton if 421g is light for a silencer as I know he makes them). When I get another carbon tube I will make another without the band, but this works for now. Again Merry Christmas, Mike







wpark89
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1/15/2022 7:58pm
lostboy819 wrote:
Yes they are, I bought a bunch of the carbon fiber Answer silencers back when they were blowing them out for $25.00 each from Tucker Rocky...
Yes they are, I bought a bunch of the carbon fiber Answer silencers back when they were blowing them out for $25.00 each from Tucker Rocky or Parts unlimited. I just cut off the tube that has the bends and weld on the correct one and I have a carbon fiber silencer. I also have several of the acerbic ones still in the package, I have used them on my YZ167 and snowmobiles and shifter karts. I love carbon fiber.











Long shot here Lost Boy….but I’ve got an Acerbis c35 silencer and I really need to find one of the eccentric mounting brackets. Any chance you have a extra?

lostboy819
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1/16/2022 11:20am
Sorry, I have used all my stash of carbon fiber silencers and the mounting hardware but will keep an eye open and grab one if I see one.
Kidkawie
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ქუთაისი GE
1/17/2022 5:09pm
wpark89 wrote:
Long shot here Lost Boy….but I’ve got an Acerbis c35 silencer and I really need to find one of the eccentric mounting brackets. Any chance you...
Long shot here Lost Boy….but I’ve got an Acerbis c35 silencer and I really need to find one of the eccentric mounting brackets. Any chance you have a extra?

Hah! I need one too. I made a strap out of aluminum but didnt finish it yet. Traced the oval profile on a 2x4, cut it out and drilled a 1.5" hole through the center. Used it as a mandrel to bend the aluminum, hole is for clamps.


MaxPower
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1/17/2022 9:50pm
What's with the road tires? Did I miss a project you built?

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