Exhaust quieting down exhaust

Discussion in '2-Stroke Engines' started by chrisalchin, May 8, 2007.

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  1. chrisalchin

    chrisalchin Guest

    g'day got my grubee 80cc engine in my frame and running, its great fun.... alittle on the slow side due to my 44t sprocket on a 20inch rim, i think ill be downsizing to a 36t sprocket shortly to increase top speed. i was just wondering if anyone has managed to quiten down one of these engines? my neighbors are complaining that its too loud... its running the stock skyhawk exhaust...

  2. Guest

    Guest Guest

    If it's a stock exhaust, most of the noise is coming from the intake believe it or not. There are ways to quiet that down, most involve a little imagination and work on the ultra simplistic air filter.
  3. chrisalchin

    chrisalchin Guest

    arrr ok.... any tips?
  4. Guest

    Guest Guest

    Make the airbox as large as practical. Maybe aluminum and pop rivet construction. Make the airbox as rigid as possible. Point the intake down and as close to the bottom of the bike as you can.

    The idea being to dampen (dull) the intake sound.

    How about adapting an existing automotive ot motorcycle airbox?

    Also, look at other things on the bike that may radiate or intensify the engines sound.

    My bike makes a bunch of noise in this order- intake, flapping/ringing sheetmetal- and other vibratory noise, exhaust.
  5. rcjunkie

    rcjunkie Guest

    Buy your neighbors some earplugs. These engines are much quieter than many diesel trucks, lawnmowers, weedwhackers, etc..

    When I was a teen, I had installed a supertrapp exhaust on my 700s nighthawk. In order to get the right carb setting (needle valve height, correct needle valves, correct size main jet etc..) I needed to do multiple passes up and down on my block. One of my neighbors called the police on me and they would come down, check that my exhaust was street legal and tell my neighbor to "pack sand" where the sun don't shine.

    Is your exhaust stock or did you gut it? My stock exhaust is whisper quiet and I can hear the gear whine above it.

    PS One way to make your neighbor come to your side is to buy him a engine and install it on a bike of his.
  6. chrisalchin

    chrisalchin Guest

    nah its a stock exhaust mate, but it sounds like a dirt bike...
  7. gone_fishin

    gone_fishin Guest

    does the muffler have a rounded cap with a screw in the middle, or a flat cap with 2 set screws on each side?
  8. chrisalchin

    chrisalchin Guest

    yeh its the rounded one with the hole at the bottom and the screw above it in the middle
  9. gone_fishin

    gone_fishin Guest

    it's the one i have, too. i've cut off the inside tube but replaced the endcap, and i'm always
    being told how surprisingly quiet it is :eek:

    you must have some really picky neighbors...best of luck with that, i wish i knew what to tell you :???:
  10. retro_racer

    retro_racer Guest

    warping it up

    Chris, This is just an idea,and I'm not sure if it would work for you.The 2 stroke motors don't always burn all there fuel,and can leave a oily mess in the exhaust.
    Here we go and this works realy well for 4 strokes,and VW's with stingers. You wrap the baffle is side the pipe with a fiberglass cloth or matt.Use a small amount of high heat foil tape to secure the cloth to its self,and baffle.Then reinstall the end cap.The fiberglass(cloth or matt) can be bought at any Walmart,autoparts store.Its used for fiberglass repair.The tape is alittle harder to get.I got some at a hardware store.They use it for heating,and airconditioning ducts to seal the seams.It shouldn't cost more than about 10 dollars,and will be enough for a couple of bikes.
  11. gone_fishin

    gone_fishin Guest

    hmmm...a loose "glasspak" might do the trick, but yeah, you'll be cleaning it pretty regularly.

    MBc EDIT: i changed my mind...don't try this at home or anywhere else, especially between your legs.
  12. retro_racer

    retro_racer Guest

    Yea but Augi thats if it dosn't burt out first with the fuel,and premix. That was my main concern with this set up.The fiberglass might act more like a spounge than a glass pack.Even though the muffler's on 2 strokes are the usualy the coolest part of the exhaust. Maybe I should have put a disclamer up there.Warning with enought heat this idea may catch fire. :cool: :sad:
  13. gone_fishin

    gone_fishin Guest

    yeah, i guess it could be a hazard.

    oh, man, i earned my own red flag :lol:

    back to topic...you could get the noise level way down if you have a way to make a longer pipe. and, i'm interested to hear if airbox work helps any, too.