Stock muffler DB killer removal – Svartpilen 401


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  • #26896
    Freccia-nera
    Participant

    Hello fellow black arrows riders,

    I’m curious to know if anyone here tried to remove the DB killer from the stock muffler, and if so, would be willing to share some infos. I’ve seen a couple videos of people saying they did it, where you could hear a distinctive sound improvement, but no footage of the actual procedure. Some say you can cut it out with a dremel, other say you have to remove the rear end that is attached to the main body by a few rivets.

    I want to do this procedure, and I plan on writing a report and posting pictures, but if anyone has some intel they’re willing to share, so that I don’t undertake this task blindly, it would be much appreciated.

    Also, does anyone know if such a mod might void the warranty of the whole bike ?

    Thanks in advance for your kind replies. Ride safe !

    #26910
    Vanessa
    Participant

    I plan to do this too, as soon as I get a moment.

    I am going to remove the muffler from the bike, drill out the rivets holding the back part to the main body and pull it out. Then cut off the dB killer tube from this part and rivet it back to the can, but using blackened stainless steel rivets.

    I’ll let you know how it goes.

    #26975
    Freccia-nera
    Participant

    Hi Vanessa, thanks for your reply ! I eventually decided to give it a go, so I’m in the middle (or so I hope) of this process. Removed the muffler from the bike and drilled out the rivets. Now I’m trying to detach the rear end from the muffler’s body but it’s kind of stuck, with not much surface to grab and pull… Major pain in the a**** so far. If anyone has some advice as to how to get this done, feel free to share 🙂

    Started the engine with muffler removed, love the sound. I guess once the whole dB killer removal is done, the bike’s going to sound close to that.

    #26978
    Luwys007
    Participant

    <p style=”text-align: center;”>Yo ! I just finished the whole mod and video recorded the whole process I’ll upload the video soon !</p>

    #26981
    Freccia-nera
    Participant

    Woaw nice ! How did you manage to remove the end cap ? Hitting with a rubber mallet ?? Mine is kind of really stuck…

    #26982
    Luwys007
    Participant

    So you rap a flat head screwdriver with electrical tape like a good amount set the driver on the lip of the baffle and lightly tap all around and it will slowly start coming out ! the harder task for me was removing the baffle as I don’t have the greatest Dremal

    #26987
    Vanessa
    Participant

    This is really interesting! Hopefully some pics/vid will follow so I can get some tips from you guys. I could really do with knowing what size rivets I need to buy? I was going to use a slide-hammer to remove the end cap, we’ll see…

    #26991
    Freccia-nera
    Participant

    @Luwys007 – where did you cut off the dB killer ? Here is where I cut it off, but now I’m wondering if it wouldn’t have been better to cut only the small cup ? Or behind the cup, trimming just the rest of the tube ?

    where is the best cutting point for the DB killer ?

    If anyone has some insight on this matter, I’d appreciate your feedback greatly, before putting everything back together. Thanks !

    P.S. : @Vanessa, once the whole process is completed, I’ll upload all the pictures with explanations. Possibly tonight or tomorrow.

    #27004
    Freccia-nera
    Participant

    Okay, so here it is, a few pictures and details about the DIY stock muffler dB killer removal process. I should state that this is a pretty simple and straightforward mod to do to your bike (as long as you have the proper tools) and that the sound of the bike is definitely vastly improved. Also removing the dB killer is permanent (unless you weld it back on).

    Tools needed :

    Allen key – Torx key – Wrench – Rubber mallet – Drill – Dremel (ideally but a metal saw can also work) – Rivet gun – 6 x 4.8 sized rivets (slightly bigger or smaller might work too, don’t know much about rivets…).

    I didn’t have a rivet gun so I picked one up from amazon for 15 euros, rivets included, and borrowed a Dremel from a friend. Cutting through the db Killer’s metal body consumed only one “heavy duty cut off” wheel.

     

    1) make sure that the pipe is cold and unscrew this bolt (Allen key) :

     

    2) Near the passenger’s right foot peg unscrew this bolt and nut (Torx (which can be found in the “repair kit” under the saddle) and wrench) :

     

    3) Remove the three torx screws that are holding the muffler’s bash guard/protection in place :

    Note : This has to be done to access one of the 6 rivets

    4) Simply pull aside the muffler’s bash guard/protection like so :

     

    5) Drill out all 6 rivets. Don’t just drill the caps, go through the rivets, because the rest of the rivet won’t fall off inside the muffler because of the glass wool thermal shield that is stuffed against the end cap’s wall :

    Note : at this point I had only drilled out the caps, you can still see the rest of the rivets bodies stuck in the holes. The picture shows only three rivets, but obviously you have to drill out the other three on the other side of the muffler…

    6) Apply some WD40 to the ledge, where end cap and muffler main body connect. Wait.

    7) Use the rubber mallet to strike slantwise the ledge of the end cap. This really didn’t do any damage to the paint nor did any dent into the muffler’s body. I had to hit it two or three times with some force and it popped right off.

    8) In my case the glass wool was sticking to the end cap, so when it popped off it pulled some of the wool out. This was a bit of a mess. I recommend using working gloves (wool is very itchy), and possibly a mask, because the air was instantly filled with small fibers. I teared the wool appart from the end cap.

    Note : At this point you might want to get rid of the old rivets left overs that are tangled up in the glass wool.

    9) Now that you have the end cap free, cut out the dB killer at the desired length. I had pretty much no idea what I was doing since this is the first time I was removing a dB killer so here is where I decided to cut it off :

    Note : only realized after I had already done the cut, that the cap/cup might be of some use and that you’re supposed to maybe keep it in ? After this mod I didn’t notice any issues in terms of engine response or whatever… To achieve this cut I went through the end cap with the Dremel and cut it from the inside.

    10) Once the cut is completed and the dB killer cut off or trimmed to the desired length, simply put the end cap back on, stuffing back the excess glass wool inside the muffler’s body. Use the mallet to get it back in place so that the holes align properly :

    Note : You might want to clean the remaining WD40 from the ledge prior to reassembly.

    11) Simply use the rivet gun to put new rivets in place. I used 4.8 sized rivets, they fitted perfectly :

    Note : be careful not to scratch the muffler with the rivet’s stem protruding from the gun as it snaps off while you’re applying quite a lot of force on the gun.

    12) Clean the muffler with a cloth to get rid of any grease (WD40, dirty hand/gloves etc), put back the bash guard/protection, then put back the muffler in place, following steps 1 to 4 in reverse order.

    13) Enjoy the much improved sound !

    Conclusion and personal note : I really like the sound of the bike without the dB killer much much more. It isn’t necessarily much louder, but the tone is really different. Using quite subjective impressions and vague terms, I would say that the sound is much “rounder”, pop’s a lot more (especially down shifting), is deeper. It simply sounds 100% better, very close to what my father’s 1984 Honda XL 500 R sounded like (also single cylinder and absolutely not Euro 4 or 3 compliant obviously), but better. It was the first bike I ever rode and now my 401’s tune sort of has a nostalgic ring which I like a lot. So to sum it up, this is a very simple, cheap and effective mod, that will let you enjoy what I would call the true sound of mid sized single cylinder engines.

    If you have any questions or want to share some feedback from your experience going down this road (no pun intended), I would be glad to read it.

    Ride safe !

    #27010
    Vanessa
    Participant

    Hi, that is a really good tutorial! Thanks for putting it together.

    I have a couple of questions if you don’t mind:

    With the dB killer removed, what is stopping the wool from coming out of the end of the exhaust?

    Can you just remove all of the wool from the exhaust can? If so would that make it too loud?

    I’m interested to know if @Luwys007 made the same alterations as you, and what their thoughts are on the new exhaust sound.

    Thanks again, it’s much appreciated.

    #27013
    Freccia-nera
    Participant

    @Vanessa, you’re welcome. Concerning the wool : as you can see there’s still a small piece of tube attached to the end cap, which makes for a ledge that I think is quite difficult for the wool to overcome. Also, the wool is very densely packed, in the whole muffler’s body, so once it’s stuffed back it really sits there and isn’t flying around. Also, once you remove the end cap, you’ll see that there’s some sort of tube shaped grid in the center of the body, where the fumes go through, which will also prevent the wool from moving around inside the muffler’s body. To give you a clearer view of the whole muffler, here’s a very basic sketching of it :

     

    About removing all the wool, I’m not sure. It’s a good question, but I guess the wool serves as a thermal shield, so maybe taking it out will have consequences on the muffler’s body on the long term (repeated overheating, paint might eventually crack, etc). If you remove the wool; you’ll have to remove the brass foil wrap and possibly the cylinder shaped grid as well (as I’m not sure what’s holding it in place actually). Also I think that as long as the catalyser is still in place the bike won’t sound too loud. I had the engine running while I had the muffler off the bike and the sound was nice, but not extremely loud at all. Let me know if you eventually decide to go down that route.

     

    Hope this helps, if you have any other questions, fell free to ask !

    #27031
    Luwys007
    Participant

    Thats an awesome write up ! really helpful, for any if you who are interested here is how i did it ! i took out the entire baffle ! really simple process !

    #27037
    Vanessa
    Participant

    Not sure what gives but this forum can be a bit flakey.

    I posted a detailed reply and it just disappeared.

    Going to try on another computer.

    #27045
    Luwys007
    Participant

    So i decided to take both the DB killer cap and DB tube and i love the results much more deeper sound.

    i am just glad my bike doesn’t sound like a sewing machine on two wheels lol

    i have been riding with this mod for about a month and have had no issues also!

    #27046
    Luwys007
    Participant

    @freccia-nera im also inerested in knowing how you where able to get the tube removed like that did you just shave down the welds on the inside of the tube i worked on those welds for grueling amount of time.. lol finally i decided to screw it and just take the entire db assembly out i knew by doing so i would git a bit more deeper sound quality then by just taking out the tube !

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