Lawn Mower Mufflers...

Discussion in 'Motorized Bicycle General Discussion' started by ferball, Aug 13, 2010.

  1. ferball

    ferball New Member

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    I post this, because as I was working on my exhaust for the past 2 days I found very little information regarding lawn mower mufflers and their compatibility with our Happy Fun Time Motors. Lawn mower mufflers alone are worth less.

    I installed a "pancake" style muffler intended for 9-14 hp lawn mower/tractor. It was slightly less noise than just running a straight pipe, and my engine lacked "pep". Now the lack of "pep" might have been due to the long pipe in front of the muffler, but noise was my primary concern, and a large pancake muffler was almost useless. I do have plans to experiment with "stacking" mufflers, but I did not feel like throwing money at it this week.

    I have since reconstructed my kit muffler and put that in front of the pancake muffler and my exhaust has a nice sound to it now, it chugs and pops more than whines.

    Other side note which will not be news to most here, the pipe length before hitting your muffler makes a difference in performance, I am sure if you go to short that can be bad, but going to long is bad as well. Rudimentary pipe tuning is just finding the right length.

    I have to post picture of my new exhaust, but I did build a weld free set up from about $20 dollars worth of parts from Lowes. I do realize I could have bought a new stock muffler for about that, but the project started off only costing $5 then $15 dollars later it worked...
     
  2. jburr36

    jburr36 Member

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    I'm not sure regular lawnmower mufflers would work for these chinese engines. Mufflers work by redirecting soundwaves into a chamber tuned to the specific frequency of sound that the engine makes in order to cause a 180 degree inversion of the sound waves as they exit the chamber. What this does is allow those inverted sound waves to mix with uninverted sound waves which in effect causes them cancel each other out and nullify the sound. These HT mufflers are really crude and not very precise which makes me somewhat surprised they work as well as they do even though they are still kind of loud.

    Since mufflers are tuned to specific engines they cannot be mixed or matched and get decent results especially if the engines operate on vastly different RPMs and bore sizes like our HT 2 cycle and 4 cycle lawnmower engines.
     
  3. ferball

    ferball New Member

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    I learned all that with my foray into exhaust building, it was fun and informative. I did add the lawnmower muffler as an after muffler, changes the sound a bit, but does not make it any quieter.
     
  4. Kevlarr

    Kevlarr New Member

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    I wonder what a HT would sound like with a Supertrapp on it?

    [​IMG]
     
  5. ferball

    ferball New Member

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    I wish I had the money to find out...
     
  6. Dave31

    Dave31 Moderator
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  7. Goat Herder

    Goat Herder Gutter Rider

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    I wondering if'n I should get one of those for my Morini? Its another thunk right there.
     
  8. Kevlarr

    Kevlarr New Member

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    Good idea! Never thought to get one big enough to put on the original muffler!
     
  9. jburr36

    jburr36 Member

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    I forgot to mention that most 2 cycle engine mufflers are designed to add a slight back pressure pulse to push as much raw fuel/air mixture back into the cylinder during the intake/exhaust cycle. A well tuned muffler for a two cycle engine not only makes it run quieter but also helps maximize the engine's performance and fuel efficiency.
     
  10. Goat Herder

    Goat Herder Gutter Rider

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    For me it would go after the tuned pipe of course. Not in place of..
     
  11. ferball

    ferball New Member

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    I was running a longer pipe than stock, longer by about 18 inches. I shortened it back to about stock length so it would fit on the down tube, I have noticed that low end lacks some of the pep the longer pipe had....
     
  12. kipharley

    kipharley New Member

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    Hi,Guys.Check out the exhaust I have started building.using some stainless flex pipe.
    Works super.Good low end I can take off pretty easy without peddling and I weigh 220 with a 44 tooth sprocket.
    Top end doesn't seem to be effected either.
    And it's tucked out of the way of everything.
    Go to Pics Forum it's under Blue and white schwinn.
    More pics to come after I get this thing ironed out.
     

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