Std exhaust mod...not

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stv1jzgte

New Member
Feb 11, 2009
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australia
Hi guys n gals,
Well ive Had my Gas man bike 49cc for nearly a week now haha and have been playing with the exhaust a lil, The day i got it i wraped some glass insulation i had around the baffle and put it back together.
i bit quieter for sure and i left it as until today when i pulled all the innards out, then put back together and went for a ride.
How did it go?
Crap! first up super super loud.
no power down low
no more power up top

I will be putting it all back together before i ride it again for sure.
Note the leak in the bottom of the pipe weld or lack of weld, its only welded over the top! i will fix this tomorrow at work along with matching the ports!
steve

.wee.
 
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schwallyjdog

New Member
Feb 11, 2009
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Bellevue Ohio
I replaced the baffle with one from a pocket bike and it has done alright but I ordered a stock one the other day because at wot it hesitates off and on. I am hoping the stocker will fix it. I also wrapped my exaust and enjoy the protection of it and wonder if it ads performance.
 
europorsche914

europorsche914

New Member
Jun 18, 2008
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Lancaster, PA / Newark, DE
Here it is: I made it out of exhaust tubing of varying diameters but it is all 16 guage which helps keep it a little quieter (the cones amplify the sound and when made out of a thinner guage it is louder (my friends was made from 20 guage and is significantly louder)). The muffler is all 2" exhaust tubing with steel wool packing around the 5/8" pipe running through the middle of it. A series of 1/4" holes, 90 degrees from each other and .5" in between them was drilled into the 5/8" tubing. This allows the noise to be cancelled out with out impeding flow. -Justin
 

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toytime

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Mar 20, 2008
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Ontario
Very nice, I can see how the thicker metal would be better, less of a "ring", I guess. I wonder what ours are made of.
To get the cone shapes, did you slice the pipe and leave the worked on areas where they can't be seen? If so, did you slice it all the way from end to end or did you stop near the end?
 
europorsche914

europorsche914

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Jun 18, 2008
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Lancaster, PA / Newark, DE
the pocket bike pipes are like 24 guage or less I use to have one of those before I made my own. I could not find a piece of tubing large enough so I cut it end to end an welded in a triangular piece of metal to bring it to the correct diameter. At its largest diameter I believe it is 3.75". I then ground the welds smooth to make it look better. Many people can go to local muffler shops and get larger diameter pipes then me (largest pepboys sells is like 2.5"). The problem with the pocket bike ones is they drop down to a much smaller diameter, not anywhere close to the exhaust port. I built a pipe like this one for my friend and noticed his motor pulled a little better than mine due to the straight section in the center on the chamber. I then built myself a pipe and in my opinion produces more performance than the pocket bike expansion chambers and the homemade expansion chamber cost $16 for the tubing and im sure i could have gone to a local muffler shop and got it for less.
 
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stv1jzgte

New Member
Feb 11, 2009
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australia
Hi Guys, well i have done some more modding to the exhaust, i have extended the centre section by 100mm and made a new baffle inside it, i drilled holes all through it then Nippled it! ie i stuck a screwdriver in the holes and bent in the direction of the flow so the air travels to the insulation. i used cotton exhaust insulation not steel wool.
Resonators for cars are either straight cut (straight through) or Nippled as ive done to this. i also made the outlet18mm

Well its louder but heaps deeper! and its got more down low and i went from 51kmh to 52.5!
 
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stv1jzgte

New Member
Feb 11, 2009
489
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australia
impression said:
nice work :)

i wonder, if you could keep the 'deepness' and make it quieter by making it out of thicker metal or wrapping the pipe ?
Click to expand...
Well the end cap at the primary pipe is std thinkness the centre section is stainless ( the worse for sound) the baffle is 1.5 mm mild steel and the outlet end cap is actually a fence post cap!

Told you i could be bodgy! nah was all i had lying around at work!
 
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impression

New Member
Feb 26, 2009
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Syadney,Australia
lucky, i think my exhaust is broken, there's a metal filing or chip in there that keeps rattling around and the end cap won't come off at all, it's like melted shut or something.
 
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toytime

New Member
Mar 20, 2008
550
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Ontario
I'm sure you do know that there is a screw holding it in place so I guess it's rust. Maybe a pair of vise grips would help you to twist it out.
 
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