Four-stroke muffler thoughts?

[jellywrestler]

whacking together a muffler, exhaust hole
cross section 645 square/mm about a square inch and what i will have is the tailpipe blanked off at the other end so my question is what's the best set up for holes in that part for muffling as well as free flowing gases.

muffling insert approx 250mm long and wont be removeable to repack etc

how many holes, what size, what format ie holes or slits with indents etc etc
it's a 250cc single

[Motu]

I just covered all bases as far as hole size goes....they work pretty well, it's a gutted system, collector and mufflers and does 94db.

http://i1009.photobucket.com/albums/af212/bmwr65/P3100135_zpsdd697141.jpg

[F5 Dave]

It's four 250 singles? Volume is key, that might be an issue. Reversals are useful to take sound energy out. That might be an exercise in miniaturisation.

[Drew]

I think the bucket guys should be able to give good advice, (not that their bikes are anything close to quiet. Grumph is real clued up on that shit too.

I fluked it on my bucket with muffler that shouldn't quieten down the thing at all. But the pipe is long and muffler underseat.

Depends on what performance you're after, have you considered a chambered muffler? Not that a quick scan of my weak mind can think of an easy way to do that, but it's certainly how bike and car manufacturers get around the issue.

[Drew]

Just realised, so the muffler is gonna be 450mm-500mm long in total? 1" perforated pipe straight through a piece of 3" would keep it pretty quiet wouldn't it?

[jellywrestler]

It's four 250 singles? Volume is key, that might be an issue. Reversals are useful to take sound energy out. That might be an exercise in miniaturisation.

i'll be duplicating it four times so what i essentially have is a 250 single with one square inch of outlet area.
i don't understand your word reversal though Dave

[jellywrestler]

Depends on what performance you're after, have you considered a chambered muffler? Not that a quick scan of my weak mind can think of an easy way to do that, but it's certainly how bike and car manufacturers get around the issue.
it's not about performance as much is trying to quiten an open pipe (warlord as i picked up the steel yesterday) although I dont want to choke it either


Just realised, so the muffler is gonna be 450mm-500mm long in total? 1" perforated pipe straight through a piece of 3" would keep it pretty quiet wouldn't it?
external is 1451mmsq internal 650mm/sq 1/12inch and 1 inch extrnal is the whole length of the pipe but this will only complicate it all to others out ther methinks

[Drew]

it's not about performance as much is trying to quiten an open pipe (warlord as i picked up the steel yesterday) although I dont want to choke it either


external is 1451mmsq internal 650mm/sq 1/12inch and 1 inch extrnal is the whole length of the pipe but this will only complicate it all to others out ther methinks
Oh right. Now I get it.

No balance pipes I take it?

Buggered if I know how you'd go about it in that instance. I imagine that the insert being as long as possible with the inside end blocked, and baffle packing from half way down it would suffice.

Picture should explain what I sorta see working.

[jellywrestler]

Oh right. Now I get it.

No balance pipes I take it?

Buggered if I know how you'd go about it in that instance. I imagine that the insert being as long as possible with the inside end blocked, and baffle packing from half way down it would suffice.

Picture should explain what I sorta see working.

packings not an option really as it's going to be one peice and nee chrome plating...

[Drew]

packings not an option really as it's going to be one peice and nee chrome plating...That just makes it difficult, can't be impossible though.

Would it matter if the packing got wet while it was in the chroming tank? Long as it's clean it shouldn't contaminate the....broth. (Fucked if I know what the water mix in the tank is called).

At the halfway point of the perf in my picture, is a plate. It could be sealed up with a bit of silicon. Wrap the perf in tape. That'd keep the juices out.

Or seal the ends. Wouldn't they need to do that anyway, or do they let the inside get chromed at the same time?

[jellywrestler]

That just makes it difficult, can't be impossible though.

Would it matter if the packing got wet while it was in the chroming tank? Long as it's clean it shouldn't contaminate the....broth. (Fucked if I know what the water mix in the tank is called).

At the halfway point of the perf in my picture, is a plate. It could be sealed up with a bit of silicon. Wrap the perf in tape. That'd keep the juices out.

Or seal the ends. Wouldn't they need to do that anyway, or do they let the inside get chromed at the same time?

it's more about it getting it in there, chrome by nature wont go up the guts of the pipe, if anything i'd be packing wire netting down there on assembly, at the end of the day whatever i do will be a vast improvement on what's there now...

[Drew]

it's more about it getting it in there, Assemble my baffle design, with the reducer from the big pipe to the little pipe on it. And the plate for in the middle.

Wrap the packing around it and tape it tight as a mother fucker. Slide that in, and weld it up. Send it for chrome. Boom, shiny quiet pipes:2thumbsup

[Grumph]

whacking together a muffler, exhaust hole
cross section 645 square/mm about a square inch and what i will have is the tailpipe blanked off at the other end so my question is what's the best set up for holes in that part for muffling as well as free flowing gases.

muffling insert approx 250mm long and wont be removeable to repack etc

how many holes, what size, what format ie holes or slits with indents etc etc
it's a 250cc single

Put a bulkhead at the front end of your piece of tube. The tube should be the smallest perf available - from memory, I think 3/4in od is available. The bulkhead has the front end of the tube welded into it, at least 3 tags bent back on the OD so it can be slipped into the can.Drill holes in the can to match the tag position, rosett weld, grind clean pre chrome.
The bulkhead can have a ring of holes 5, 6 8 mm whatever fits in which in themselves are a silencing element.
Weld it all up, clean up and chrome. Forget....

[Drew]

Put a bulkhead at the front end of your piece of tube. The tube should be the smallest perf available - from memory, I think 3/4in od is available. The bulkhead has the front end of the tube welded into it, at least 3 tags bent back on the OD so it can be slipped into the can.Drill holes in the can to match the tag position, rosett weld, grind clean pre chrome.
The bulkhead can have a ring of holes 5, 6 8 mm whatever fits in which in themselves are a silencing element.
Weld it all up, clean up and chrome. Forget....
Open "paint", and draw us a picture would ya?

[F5 Dave]

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?

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=284768&d=1373189420

[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?

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=284768&d=1373189420

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:love:

[jellywrestler]

It's all worth it, just to be noticed:love:

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

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.:shit:

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.

http://i1009.photobucket.com/albums/af212/bmwr65/2013-09-02164614_zpsc21f863f.jpg

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

http://i1009.photobucket.com/albums/af212/bmwr65/P9040162_zpsd44c4f9b.jpg