Muffle That Noisy Thing!




this instructable will show you how to make a quieter muffler for your go kart .or any other noisy contraption you have

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Step 1: Tools and Materials

i'll start with safety .which is where we should all start


-welding mask
-welding gloves
-welding leathers
-leather work gloves
-safety glasses
-ear muffs or plugs

now that we've got the thumbs up from


-band saw
-drill and drill bits
-welding hammer
-wire brush
-tin snips or very strong (CRAFTSMAN) shears

these aren't needed but the make life easier


-wire brush attachment for your drill or grinder
-spur bit
-drill press
-pneumatic air punch/flanger (compressor to power it)
-high temp spray paint

now the stuff that makes up the muffler


-metal cylinder with a fairly large volume
-metal scrapes roughly the same thickness of cylinder walls
-1/2" threaded rod .several feet in length
-1/2" tie rod couplers
-1/2" nuts
-thin metal flashing (hazardous but galvanized will work)
-1" pipe .several feet in length

Step 2: Whats a Muffler Anyway?

before we start working you might want to check out this video to see the principal behind the muffler

for my muffler body i used a small nitrogen bottle from a broken welder my dad picked up in someone's trash .as you can see even before i cut it it had seen better days .it was a good thickness (1/10 of an inch or so) so i didn't just blow holes in it when trying to weld .if you have a welder with more precise temperature settings you can of coarse use a something thinner .the other thing you will need is some pipe .for the tail pipe section .and you should have the muffler thats being replaced as you will need the exhaust manifold from it .on mine they were welded so i cut as closely to the muffler as possible to ensure i didn't have a lack of space issues later on

Step 3: Slice and Dice

you don't have to cut the tank (new muffler body) in the center that's just were i chose to .once you have the tank cut where you want .you need figure out where you want your tail pipe to go .i choose to have mine on an angle as you see .i also rounded the pipe to fit the contour of the tank

.once you know where the pipe goes trace around it .and drill holes inside the circle/oval/what have you .there are plenty of ways to do this .i drilled holes close to one another around the shape for where the pipe was to go .then with the persuasion from my hammer i knocked the center piece out and cleaned up the edges with a spur bit i put in my drill

.to attach the manifold you will need to first remove it from the old muffler .and then place it back on the engine block so you can hold up the part of the tank you're going to weld to it and make sure you have plenty clearance .one you’re happy with that trace around the manifold so you can make the hole .you might also want to mark manifold and tank with corresponding lines so you have the correct orientation when you start to weld

Step 4: Bring the Heat

you should start by tacking the manifold and tank together and give it a test fit .because now would be the time to get it right .once you've seen that its in the proper place do your finish welding

do the same with the tail pipe and tank .though you more then likely won't have to test fit it

i bet you have been wondering how these will fit back together if i've cut them apart .you will need some strips of a sheet metal about the same thickness of the tank walls .i hacked apart a piece of square tubing for mine .but once you have them you want to tack it in place with an appropriate amount of overhang .the metal is now hot so with your hammer start at the tack point and tap it to get it to start conforming to the tank .make another tack and tap it again .repeat until you have your strip wrapped around the tank one you have added enough strip you should place the two halves together to make sure it will be able to fit in there snugly .you do NOT want to weld on the inside of this or the other half of the tank will not fit into place and if you are using more the one strip of metal to wrap it make sure your butt welds don't penetrate to inhibit the two half from coming you also want to take care as not to weld your halves back together

the final thing you need to weld is bracket to help support the new and much heavier muffler .i made this bracket from the square tubing i hacked up .there was already a treaded hole on the top of the engine which had a wire cage secured around the old muffler to help keep burns to a minimum .this bracket i also contoured to fit around the muffler .just to get as much support out of it as i could .I had to cut ,drill ,grind ,bend ,cut ,then grind some more but after I got it welded in place and bolted to the engine the muffler is now a part of the go kart .you shake it and the whole go kart shakes

Step 5: I Hope You Don't Get As Baffled With This Step As I Was

ok so i'm talking about the baffles that go inside the muffler and not being confused .the first thing you should do is drill a 1/2" hole in the top and bottom half for the threaded rod which not only holds the baffles but also holds the muffler together .is a good thing you offset the tail pipe and exhaust manifold

now that that is done .you need get the metal you're going to make the baffles out of .for this i used galvanized flashing .it doesn't have to be thick because the only thing it will be holding back is exhaust .you need to get the measurement of the inside diameter of the tank .then divide that by two (sorry for dumbing down) make a compass and start drawing circles .remember to makes sure you mark the center of each circle because you will need to drill a hole there

now its time to kill your forearms .grab your tin snips or some bastard shears and carefully and precisely cut out all your baffles i ended up cutting about 18 abut only used 13 in the muffler the five i didn't use in the muffle i used to practice cutting the air holes .and i'm glad i did

once you have all you're baffles cut drill a hole in the center of each one .the way i did this was individual drilled a small hole in each baffle .then i used a small machine screw and bolt to hold them all together .once they were together and as tight as possible i used a buffing/sanding pad on my grinder to smooth the edges to all the same circumference and make sure the fit inside the new muffler would be as snug as a bug in a rug on the drugs

when i had the fit like i wanted i clamped the baffles together to enlarge the hole in the center to 1/2" .i found it easiest to slowly work my way up threw the diameter drill bits i used .i tried starting with the 1/2" on but it caught and the drill wanted to spin my arms off .so working your way up to the 1/2" is defiantly the better way to go

now that you've got that out of the way lets talk about how the exhaust will be getting threw those baffles .you're going to need some hole in them .or some slots .yet you could just cut off one edge to make a small opening for the gases to escape threw .they way i went was pneumatic hole punch .and punched slots (one hole at a time) in the baffles along the outer edge

Step 6: Fung Shui

arangment of the baffles (by that i mean the holes threw which the gases pass) .as well as distance you place the baffles from one another does matter .and will result in different sounds and airflow threw the muffler and effect preformance of the engine

the first set of baffles have three slot and the top second set have four of slots .having the holes staggered so the gases can't just pass right threw .there is a nut in between each baffle .with a small open chamber at the bottom where the exhaust enters the muffler then a the first set of six baffles .then into a larger area in the center of the muffler .finaly threw the last set of seven baffles with four slots in them after which is a final small chamber and the tail pipe

.this is just the set up i came up with .i made the muffler easy to take apart for the purpose of playing with it and the different nosies i can't get out of it

Step 7: "throw Another Muffler on the Bar-b"

is is optional but recommended .get some high temperature paint .paint it .and grill it (to cure the paint for maximum temperature resistance ,follow the directions on the paint can)

Step 8: Tear It Up .quietly

while making this muffler i played with it just to see what different sounds i could get .when i had the manifold welded to one half of the muffler body i put it on and ran it around .the large unobstructed path the gas had to escape threw improved performance of the engine but acted like the horn amplifying the noise to an obnoxious level . yet putting the two halves together not using any baffles did quite it some and gave it kind of an old tractor "putt putt" sound .but installing all the baffles and having the muffler fully assembled reduced the noise to an estimate 3/4 what it was originally

the reason for wanted a quieter muffler? .i live in the city and there are some places to ride a go kart but not may .so if your quite about it there's less chance you'll get the cops called on you by the old hag next door

i hope you liked my instructable .and as before if you have any suggestions please feel free share

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    30 Discussions


    4 years ago on Step 8

    I hear you about "the old hag next door". (I also own a kart and live in the city.)


    5 years ago on Introduction

    Thanks for the ible. Just looking to quiet my old lawn mower.


    10 years ago on Step 8

    what about a mini dirt bike muffler and for someone who can't wield ...yet.....

    3 replies

    Reply 6 years ago on Step 8

    sorry i'm just now replying i didnt realize you had commented till now .anyway .it might be possible ,a screw in muffler made of gas pipe might work better since the muffler intended did screw in


    Reply 6 years ago on Step 8

    i didnt build the cart .it was originally bought from a store but was well past second had when i bought it


    yeah a fire extinguisher would make a great muffler housing .its lighter then the cylinder i used but not so light that it won't blow threw when welding .if i make another one i think i'll have to use your idea and use an old fire extinguisher


    cool, i am making it for a snowblower, i need it to be quiet because i will be using it very early in the morning.


    11 years ago on Introduction

    i like my stuff loud but there are trails near my house and the people around the trails are mean and get mad whenever i ride so all my stuff has homemade silencers for them that are removable

    1 reply
    Country dudenibbler125

    Reply 10 years ago on Introduction

    Ya I was thinking about taking a pocketbike to a campsite for getting around and make a track system for the back and make-shift ski for the front (the hole camp is sandy) But to keep it down I may hafto make one of these for it