Repacking 4T muffler?

 Trying to be a good steward to the sport and want to repack the stock muffler (14' 520RS). I was warned not to attempt this by the local Beta dealer because it's such a bitch. But it's a rainy day and on my list. Plus I've "got an awesome set of tools" so figured WTH. I've searched high and low for any muffler data on this bike and have never seen a repack.

Drilled the rivets (ss, use a cobalt bit!), soaked the end caps in tri-flow and started walloping with a dead blow hammer. The headpiece side came off with quite a bit of effort. 

This can has a divider so the packing is 2 short pieces on each end. The core is tapered and goes the whole length of the muffler. 

There is nothing to grab on the end cap. There is a small spot I could fish a wooden dowel through to a semi flat spot on the end cap. Pounded the dowel on the concrete (Hard) and it splintered. Cap didn't budge.

Heated the aluminum muffler can around the end cap with a torch and tried again. Splintered another dowel. Then I tried hitting the divider, thinking it's part of the end cap assembly  but no go.

The only thing I can think of now is to spot weld a stud on it to grab with a slide hammer.

Or just re-rivet the end and just replace the first section packing but that sucks.

I'll contact Tim at Beta and see if he has any advice. Has anyone repacked their Beta muffler before?

Thanks all,







Edited by H20ENG

This is timely as like you, I want to replace my packing to see if it will quiet the bike down.  I'll be looking forward to your next posts on this.  Thanks for starting it.  

Did you get the packing from Beta?  

As soon as I brought up the topic he just shook his head at me and said "don't even try" Lol.

 I have to do everything the hard way. I had some Silent Sport packing but turns out it's too small (likely 2T) so I'll check pricing on the OEM. It seems good stuff- reflective woven wrap around long strand fiber. 

Entire rear section packing gone and only remaining in front was in the end cap.

For now I've soaked the joints in penetrating oil and will try again tomorrow 


I remember two mufflers that I had (tried) to take apart.  One was from a ProCircuit muffler for a CR500R and the end cap took a LOT to get off as it seemed to either have welded/corroded or was just stamped together so tightly I had to pry and pry to finally get it out. 

Same with the stock muffler for the same bike.  It was a holy horror show to get off.  I think that the machine that presses the end caps on just does it so well or so tightly, it makes us wonder why they even put so many rivets to hold it on when if they put two rivets on the caps would still not come off.  

I'll buy the packing that Beta sells.  I hope you get the other end off and then tell/show me how to get it done as this is something I totally want to do.  With 2,1xx miles and 118 hours, I"m wondering what the packing is like.  I did also just buy two packages of AL rivets, 1/8" and 1/4" so I'm ready to get it done.  

What did the packing that you had taken off the lower baffle look like?  The longer piece?  

Edited by Ben500RR-S

I've repacked quite a few. Sometimes the rtv silicone is a bitch. This would be easier if there was something to grab. I don't want to just pound on the center divider without talking to someone because I can't afford a new one.

Edited by H20ENG

Do you think that maybe if you stuck the thing in the freezer overnight, then took the torch to the muffler metal that surrounds the cap, that it would help to expand the metal fast enough that  it might slip out easier?  That is what I would try next.  


I wonder if putting the end cap in a big vice and then pulling on the muffler might do anything to help the separation.  In the past I didn't mind prying the metal/aluminum around the cap  as I'd just pound it back into place once the cap was off as the first time was the biggest PITA, but once I knew I got them separated they'd come off easier next time.  I also just used screws to put the caps back on as  I was always repacking my 2stroke mufflers to keep the bike quiet.  I might not need to worry about it as much on this big 4 stroke.  

That's a good idea. I was hoping the aluminum expanding faster than the endcap would do it, thus the torch. The freezing adds another layer of expansion.  The geometry of the end cap makes it really hard to grab. I'd have to take it to work for a vise that big.

Hopefully after soaking overnight it may pop loose.

Re: the packing, it was basically all gone. It was about 2" long packed in the end cap. The picture I showed was all that was left. 

Seeing how empty this thing was, I'm excited to get it repacked fo see how quiet it gets.

The older I get, the more being loud bugs me. We all get so much bad press from a few bad apples and idiot Sierra Clubbers that we won't have anywhere to ride soon. Hoping to do my part.

So, anybody else repacked their mufflers? Please share.

You don't take off the end cap on this muffler, you slide off the entire canister.

I don't understand that Kran. There's packing on both sides of the center divider.  Can you explain further?


8 hours ago, H20ENG said:

I don't understand that Kran. There's packing on both sides of the center divider.  Can you explain further?


No you are right, both end come off. I was thinking about my last KTM.

Victory! Letting it soak overnight did the trick. The center divider is welded to the end. I was able to use a 2x2 to tap it out. There's a very thin (1/4") piece of foil backed packing around the rear section.

I checked and saw prices from $75-120 for Betas kit so won't be buying OEM.

Tim Pilg with Beta got back to me (try that with Honda hah!) but unfortunately didn't have much more info.

I wish I had a picture of the muffler guts beforehand. I would have beat it out yesterday. This should be in the manual!

This makes this task much easier now I know where to smack it.

Something I noticed: muffler is stamped "Arrow screen type spark arrestor" yet there is NO screen inside. Hmmm. Maybe because the flow needs to change direction inside is sufficient?

Hope this helps anyyone hesitant to tear into their Beta mufflers. I sure was.








2x2, pound it on the inside and the end cap will come out  Soak overnight in penetrating fluid first  


Does the engine-side come out easier?  


I'll be curious as to what you will be using to repack.  The Beta stuff is expensive but it is perfectly fitted.  It is crazy how expensive the muffler is from Beta, something like $749 or more.  

Local Beta dealer says $130 and on backorder. That's crazy for such a small amount of packing. The rear section was 85% intact so I'll just add some there. The front section is like 8-10" long.

I just bought some generic FMF "everlast" packing. Get the long/continuous fiber stuff.

The front section has the leverage of the pipe so I just tapped it back and forth with a dead blow working it loose.

I can tell you this muffler, even with the pipe is light! I put an E2 on my WR and no way it's this light.

Dealer says the FMF Q works better than stock but is just as loud. I'll try this first.

Reused the thin stuff at the end and added some new.


Cut the new pillow to length. Cut angles on the pillow to fit the front cap then wrapped it. The perf core angles up so used the leftover pillow scrap strips to fill the bottom. Wrapped it in tape then added some heavy foil (no idea if this will do anything but the original was reflective inside) if anything it helped slide it in.

Went together fairly easy and re-riveted it. I'll install it and see how she sounds.




Edited by H20ENG

Do you think it’s possible to chop 4-5 inches off the backside behind the mounting tabs???


In order to shorten the overall length of the muffler.


You had me at Triflow.

37 minutes ago, surfer-dude said:

Do you think it’s possible to chop 4-5 inches off the backside behind the mounting tabs???


In order to shorten the overall length of the muffler.


Sure, would only need to cut the perf core to fit. It's got a good taper and points up so may need to tweak that.

37 minutes ago, hondaxr650rrrr said:

You had me at Triflow.

Hah! Use it every day at work... on everything. Love it.

Well this may have been a huge hassle for no gain. Seems just as loud. Hopefully after the pillow fabric burns off it will quiet down some. Time will tell. Changed oil and filter and will take it for a spin.

Man, I appreciate you posting up this thread.  

I will probably just wait  and see if the motor gets any louder as time goes on as I only have 1 year and 2 months, 118 hours and like 2,200 miles.  


I think that between the intake and the small amount of packing that surrounds the perforated core, it doesn't make much difference when the packing is replaced.  

Cars/trucks have no packing, just big mufflers that quiet the exhaust and they run quiet.  It has to just be the design of the thing that helps to quiet things down as it is a big can/muffler relatively speaking.  Good to also know it is light as it seems heavy but as it is all AL, that has to keep the weight of the $800 muffler down.  

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