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MM = extra noise ? Solutions?

Discussion in 'Chainsaw' started by andy at clover, Aug 12, 2019 at 4:10 PM.

  1. andy at clover

    andy at clover Woods!

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    MM's seem to be the first line in squeezing more performance out of a saw and maybe more importantly preserving some life by allowing heat to leave.
    What about the additional noise from modifying?

    Any best method to avoid that?
    What have you all found is the best balance of relieving heat and adding minimal extra decibels ?
    Louvered gills and better or worse than just enlarging the factory port?

    The Saw in this case is a ms241 I've added to my saws and, this one will be used in urban neighborhoods for work.

    My other saws are "mine" and are all ported, opened up and loud as hell.
    For the little 241, I'll abandon the idea of a MM and just run it if It gets too loud.

    Thanks for comments and suggestions.
     
  2. TheTone

    TheTone ArboristSite Guru

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    I often do a mild muffler mod by enlarging the existing baffle holes and adding extra louvers on the shell, rather than just gutting it. If you're curious and mathematically inclined, you can calculate the percentage of increased flow. Since there is still some baffling left, the noise level is kept to a dull roar, so to speak.
     
  3. andy at clover

    andy at clover Woods!

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    ^^^^^
    Cool thanks for the reply.
    Are you satisfied with extra gains and or cooling ?
     
  4. Matt93eg

    Matt93eg ArboristSite Operative

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    Out of my saws, I have only done MMs on my Dolkita and Husky 390xp. The other saws are loud anyways.

    I don’t find the noise any concern to me at all as I wear ear plugs. I also find the ear plugs help me hear the tune better so it’s a win win IMO.
     
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  5. pioneerguy600

    pioneerguy600 Lost in Space Staff Member

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    Don`t put exit holes in the front cover facing forward, better to add an extra hole on the left rear shell with a deflector if physically possible, enlarging the existing hole to the max that the deflector will cover is a good first step.
     
  6. TheTone

    TheTone ArboristSite Guru

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    I can't give you a quantitative answer on the differences from stock. I try to get each step to around 80% of the exhaust port area. By "step", I mean each restrictive part of the muffler. For instance, on the 024 or 026 muffler (going from memory here) there are two steps that could be called baffles in addition to the exit holes. The first is the usual baffle with multiple holes. I expanded all the holes that could be reached with a drill. The second "baffle" was enlarged by drilling three holes that were not originally there. Then at the exit holes the louvers were expanded and more louvers were added on the side.
    IMG_20180627_171730_416.jpg IMG_20180627_171912_523.jpg IMG_20180627_171842_253.jpg
    By estimate combined with measurement, the flow was increased by 240%. Admittedly this is an idealized figure because it was based only on area of flow openings and ignored the fluid dynamics of air flow friction at each step. As to loudness, I couldn't tell you because I always wear hearing protection (I have noise induced high frequency hearing loss from youthful indiscretions: rock bands, concerts, dove hunts, without protection)
     
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  7. huskihl

    huskihl Addicted to ArboristSite

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    Biggest thing I've noticed when adding a deflector or enlarging the factory hole is, if you're concerned about noise, not opening the hole to the front of the deflector. Try to keep enough overlap from the front of the deflector to the front of the hole so that you can't see the piston
     
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  8. pioneerguy600

    pioneerguy600 Lost in Space Staff Member

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    Same here, I try to keep the exits covered with the deflector just to keep the racked down, exit holes on each side of the rear muffler can if at all possible, I make my own deflectors.
     
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  9. Matt93eg

    Matt93eg ArboristSite Operative

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    I used 288XP deflectors on my 390 and 6401. Here is the 6401 muffler stock vs modded. Afterwards I cleaned and repainted with black high temp paint but didn’t take pics after painting. On the 6401 I also heated the crimp, split the muffler and cut the baffle out of the inside. It’s loud but like I said I wear plugs so it doesn’t bother me.
     

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  10. Ketchup

    Ketchup Smells like 2-stroke.

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    In my experience, dual and triple port mufflers are slightly easier on the ears than a single giant hole and deflector. As stated above, straight lines from the exhaust port to muffler exit seem louder.

    Has anybody experimented with a “pass-through” style muffler? I’ve been meaning to, but I’m too busy. I like the power of Muffler mods, but I could lose the deafening crackle.
     
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  11. Brent Nowell

    Brent Nowell ArboristSite Guru

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    I keep the internal baffle as well as there is more than just noise engineering behind it imo. I do if possible try and enlarge the holes.

    Another tidbit is if you are drilling and adding a pipe, recess the pipe into the the muffler as much as possible before brazing. This will allow sound to bounce around the pipe and back inside the muffler. More surface area is less noise to a point :)
     
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  12. TheTone

    TheTone ArboristSite Guru

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    A couple of additional points: A compromise on muffler screens is using a screen with slightly bigger holes in the wire mesh. The area covered by the wire in stock screens reduces the flow area considerably. This reduction is about halved by using the next size mesh. However, this would NOT be legal if you are cutting on government land with spark arrestor laws. Also, don't tinker with the muffler if you have a fixed high speed setting or limiters. Your mixture may end up being too lean. If you want a finished look with more rust resistance, Design Engineering Inc. makes a 1500 *F black paint
     
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  13. Ted Jenkins

    Ted Jenkins Firewood by TJ

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    Where possible the muffler has to be enlarged to make the process work well. In my business I have to keep the noise close to what the factory level was period. To gain any performance the muffler has to be a little larger which always involves some welding and sheet metal work. Spending time to achieve all that does not always seem practical. If noise is not an issue open the thing up and have ear plugs close by. Thanks
     
  14. Robin Wood

    Robin Wood Go hard or go home

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    From my experience put few small openings than 1 big opening
    Use tube style exit, and stick it in more than 1/2". They run quiter and the gains are still there, deflector versions are very loud
     
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  15. EngineNoO9

    EngineNoO9 ArboristSite Operative

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    Just go deaf and you won't care anymore
     
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  16. drf255

    drf255 BAD CAD

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    The only way to get flow without noise is to have the sound waves collide and cancel each other out.

    So, as Jerry and Kevin said above, no straight shots out the front. I try to make the exhaust hit the front cover and then turn around whenever I can.

    Adding baffling can help with this.

    Screens help.

    Wrapping the factory deflector so that it’s longer can also help.

    Even when the level of noise is the same, side vs front outlets can have a tone that’s more tolerable, even at the same decibel.
     
  17. Canyon Angler

    Canyon Angler Addicted to ArboristSite

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