Four-stroke muffler thoughts?

[Grumph]

Open "paint", and draw us a picture would ya?

The hamster powering my dialup is looking sick now...."paint", whatever that is, would kill him.

Just as Spyda drew it, but with a bulkhead on the front end of the insert tube. Bulkhead has holes, insert tube is perf which is readily available down here....but we have a couple of places making car mufflers. No packing.
Any fine tuning on total noise level could be done by welding in washers on the outlet.

Personally, I'd build it up and bolt it on to test noise level prior to chroming.

This style of muffler works with mild cams and largish cylinders as the resonance frequecies are lower than a race 150cc. You've got a front chamber to slow and cool the pulses followed by a silencing section which changes flow direction thus removing energy.

Edit - just looked at pics Dave posted. Small dia perf inside the sq ends, it'll work.

[jellywrestler]

By reversals I mean changes of direction. Just went back to thread for another look at old pipes. Are there going to be any changes? Maybe some wedge type arrangement, or slip in caps?

at the mo the end caps are just that, ie 1- 1/2 inch reduced to 1 inch no muffling anywhere, i was going to extend the 1 inch squre in 250mm and drill holes in it, then i came here to seek pearls of wisdom from some and drews input too...

[jellywrestler]

Edit - just looked at pics Dave posted. Small dia perf inside the sq ends, it'll work.

extra points for diffuculty, on some pipes the 1 inch square is parrallel to the outer on some it's at an angle...
the plot thickens though,

[Drew]

and drews input too...

It's all worth it, just to be noticed

[jellywrestler]

It's all worth it, just to be noticed

it's alright Drew, I deo listen to what you've got to say as it's all food for thought and sometimes you'd be on the money. Still reckon being at kindy with ya would've been tough, they had metal toys back them not happy meal shit they've got nowadays

[Drew]

sometimes you'd be on the money. Still reckon being at kindy with ya would've been tough, they had metal toys back them not happy meal shit they've got nowadays

Bloody hope so, Alan and I have come up with all the design/fabrication on the chair.

We didn't have kindy out in the middle of butt fuck no where, Monowai village, where we lived before I went to school. I had to play in the garage to amuse myself.

[Grumph]

Bloody hope so, Alan and I have come up with all the design/fabrication on the chair.

We didn't have kindy out in the middle of butt fuck no where, Monowai village, where we lived before I went to school. I had to play in the garage to amuse myself.

i think we'd all realised you had to play with yourself....

Spyda, the good thing about small dia perf tube is how easily it bends. Make up the ends complete with curved insert tube and the bulkhead on the end, slide it in and weld.

[AllanB]

Reckon you want a core that is 'notched' for want of a better term. See below as a example.

I made one some years back to shut up a rowdy pipe as a insert -get a piece of exhaust pipe in your preferred diameter cut a number of alternating slots in it down the length and a sharp whack with a cold chisel and hammer will indent it into the pipe a bit. once finished if you look down the internals of the pipe there are triangle shaped indents. These disrupt the gas flow on it's way through the pipe reducing the sound. Worked well for my application.

Somewhere on the other computer I have a photo of my efforts. sample below is off the net - more professional!

Also check with Magoo mufflers - they sell cores of a similar nature but I doubt if they will be available in a very small tube.

[Motu]

[QUOTE=jellywrestler;1130607131
i don't understand your word reversal though Dave[/QUOTE]

Reversing the flow of exhaust gases, what most normal mufflers do. I cut open my TLR200 muffler the other day - the gases expand into the first chamber, then down the long tube at the top to the rear chamber, back through the small tube to the centre chamber and then out the tail pipe which is connected to the centre chamber. In all the exhaust gases get to expand 4 times in this muffler - you can't see the first part of the system. Controlled expansion,, that's the secret of quiet exhausts.



Who needs quiet, after more than 10 years I'm opening it up - loud pipes save lives.