ADVrider

Go Back   ADVrider > Gear > The Garage
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 05-28-2011, 07:59 AM   #1
Bronco638 OP
Nobody Home
 
Bronco638's Avatar
 
Joined: Dec 2004
Location: Itasca, IL
Oddometer: 3,550
Exhaust Pulses and Mufflers - 4 Stroke vs. 2 Stroke

I'm not an engineer but I have some idea how mufflers work to break up exhaust gas 'pulses' which reduces noise. That said, is there any internal difference between mufflers made for 4 stroke engines versus mufflers made for 2 stroke engines?

A friend gave me an FMF Power Core 2 muffler. A little research reveals that it's for a KTM 250SX. Would this muffler work on a 250cc Honda (provided the pipes match)?
__________________
There are some simple thruths......and dogs know what they are - Joseph Duemer

Andy holds the lead. And he will, all the way to the Highway. Today is his day.
Bronco638 is offline   Reply With Quote
Old 05-28-2011, 04:19 PM   #2
VonHelm
soggy doggy
 
VonHelm's Avatar
 
Joined: Oct 2007
Location: Grapevine, TX
Oddometer: 3,969
Quote:
Originally Posted by Bronco638 View Post
I'm not an engineer but I have some idea how mufflers work to break up exhaust gas 'pulses' which reduces noise. That said, is there any internal difference between mufflers made for 4 stroke engines versus mufflers made for 2 stroke engines?

A friend gave me an FMF Power Core 2 muffler. A little research reveals that it's for a KTM 250SX. Would this muffler work on a 250cc Honda (provided the pipes match)?
Functionally, all perforated core silencers are about the same. That being said, once the packing material of a two-stroke can gets oil-soaked, it will become louder.
__________________
http://www.oilandpiston.com/
Well he’s one of those who knows that life
Is just a leap of faith
Spread your arms and hold you breath
And always trust your cape (Guy Clark)
VonHelm is offline   Reply With Quote
Old 05-28-2011, 08:11 PM   #3
Truckin_Thumper
low profile
 
Truckin_Thumper's Avatar
 
Joined: Jun 2007
Location: Houston,TX
Oddometer: 28,538
A motorcycle muffler works exactly like a supressor works on a fire arm.

Figure out how to design them fused, you can make a small fortune.

Angled internals maybe multiplyed X3? figure out a way to stuff packing in each slot, or not.

If they can suppress a .50 or an M4 in burst, or any other full auto (small calibre), a measly engine should be simple. Oh yeah, make it legal for the tax collectors and EPA.

Report back with results


Oh, I can for the life of me pay $1200 to make something louder.
$1200 I want it to wipser
__________________
Hawk and some stoopit chicken are idiots
Truckin_Thumper is offline   Reply With Quote
Old 05-29-2011, 04:36 AM   #4
concours
WFO for 41 years
 
concours's Avatar
 
Joined: Dec 2008
Location: Kensington, NH USA
Oddometer: 5,193
The silencer you have will work on either. UPSTREAM, the 2 & 4 stroke exhaust differs dramatically. 2 stroke uses an expansion chamber (python that swallowed a rat look) and four strokes use a straight pipe back to the silencer. Just be sure the silecer is large enough to not be restrictive.
__________________
Too much is just barely enough.....
concours is offline   Reply With Quote
Old 05-29-2011, 06:15 AM   #5
Bronco638 OP
Nobody Home
 
Bronco638's Avatar
 
Joined: Dec 2004
Location: Itasca, IL
Oddometer: 3,550
Quote:
Originally Posted by VonHelm
Functionally, all perforated core silencers are about the same. That being said, once the packing material of a two-stroke can gets oil-soaked, it will become louder.
Is there a way to clean the packing (other than replacing it)? The can has fasteners, for the end cap.
Quote:
Originally Posted by concours
The silencer you have will work on either..... Just be sure the silencer is large enough to not be restrictive.
That's what had me wondering. So, if a muffler is sized for a 250cc 2 stroke then it should be OK for a 250cc 4 stroke. The engine displacements are the same, therefore the (exhaust) volume would be the same (even though the 2 stroke fires twice as often).

Thanks for the replies.
__________________
There are some simple thruths......and dogs know what they are - Joseph Duemer

Andy holds the lead. And he will, all the way to the Highway. Today is his day.
Bronco638 is offline   Reply With Quote
Old 05-29-2011, 08:57 AM   #6
Eggsontoast
Adventurer
 
Eggsontoast's Avatar
 
Joined: May 2010
Location: Dad's sack
Oddometer: 66
Exhaust gas dynamics?

Now there's a can of worms.

What you have to remember is the tuned length of the whole exhaust system (pipe & muffler)

If you want to replicate the standard power characteristics then get the original's dimensions; a two stroke that works on a loop scavenge principle must draw and obstruct gases from the crankcase and the muffler will play a part in doing so. A four stroke does not operate under the same principles as the inlet/exhaust phase is constant and accomplished through two crank' revolutions(one too many). The exhaust system is there to tame the power curve to a certain criteria, both four and two strokes are indeed "thermo engines" but both operate in very different ways to accomplish their objective, therefore both will neccessate specific characterictics from the exhaust system. Equipment-wise they're the same but dynamically they are not.

Get yourself some books and learn the differences because in all honnesty there is alot of differences that your average joe wouldn't even think about.

Pat
__________________
La Moto, c' est une aventure qui mene jusqu' au bout du monde...

Eggsontoast screwed with this post 05-29-2011 at 09:05 AM
Eggsontoast is offline   Reply With Quote
Old 05-29-2011, 09:19 AM   #7
rapidoxidationman
Easily trainable
 
rapidoxidationman's Avatar
 
Joined: Apr 2006
Location: The Teton Rockies
Oddometer: 8,160
Quit overthinking it.

Try it on.

If it fits, wear it. If it doesn't, don't.
__________________
Quote:
I know I'm feeling badly when I have no interest in speeding
Patrick
rapidoxidationman is offline   Reply With Quote
Old 05-29-2011, 10:27 AM   #8
Range Motorsport
Junk collector
 
Range Motorsport's Avatar
 
Joined: Nov 2007
Location: Da UP Eh!
Oddometer: 1,652
Quote:
Originally Posted by Bronco638 View Post
Is there a way to clean the packing (other than replacing it)? The can has fasteners, for the end cap.

That's what had me wondering. So, if a muffler is sized for a 250cc 2 stroke then it should be OK for a 250cc 4 stroke. The engine displacements are the same, therefore the (exhaust) volume would be the same (even though the 2 stroke fires twice as often).

Thanks for the replies.
New packing is cheap and easy to do and will need to be done even on a 4 stroke muffler. Should be about $10 for new packing at your local shop or online.
__________________
2007 KTM Superduke
SNL Will Ferrell Yoga, google it.
www.adventuremine.com
www.upoverland.org
Range Motorsport is offline   Reply With Quote
Old 05-29-2011, 12:36 PM   #9
Bronco638 OP
Nobody Home
 
Bronco638's Avatar
 
Joined: Dec 2004
Location: Itasca, IL
Oddometer: 3,550
Quote:
Originally Posted by Eggsontoast
Get yourself some books and learn the differences because in all honnesty there is alot of differences that your average joe wouldn't even think about.

Pat
Thanks Pat. I know there's more than meets the eye here. And, I have done some research. But, as I mentioned, I'm not an engineer and some of the things I've encountered are written over my head. I'd also be afraid that anythig written that I can truly comprehend would be too simplified.
Quote:
Originally Posted by rapidoxidationman
Quit overthinking it. Try it on. If it fits, wear it. If it doesn't, don't.
I already know it will (kind of) fit. I was just wondering if it was worth the effort to complete the install process.
Quote:
Originally Posted by Range Motorsport
New packing is cheap and easy to do and will need to be done even on a 4 stroke muffler. Should be about $10 for new packing at your local shop or online.
Thanks, I would assume, at the very least, that FMF would sell new packing. Since it's cheap I might as well do that regardless of the condition of the existing packing.
__________________
There are some simple thruths......and dogs know what they are - Joseph Duemer

Andy holds the lead. And he will, all the way to the Highway. Today is his day.
Bronco638 is offline   Reply With Quote
Old 05-29-2011, 01:34 PM   #10
Skippii
Hookers, my lad.
 
Skippii's Avatar
 
Joined: May 2008
Location: Richmond, Va
Oddometer: 6,492
That's a really good idea, actually.
I wonder if you'd be able to wash your used exhaust packing in your clothes washer.
With some sort of a degreaser, like the stuff No-Toil sells to clean their air filter oil, you might be able to clean and reuse the exhaust packing.
__________________
"Umm be careful what you say, this is Skippii....
You may get it delivered in the form of a shake or some interperative dance routine that involves nakedness, pizza and a stuffed raccoon..." -DCrider
Skippii is offline   Reply With Quote
Old 05-29-2011, 03:52 PM   #11
Eggsontoast
Adventurer
 
Eggsontoast's Avatar
 
Joined: May 2010
Location: Dad's sack
Oddometer: 66
Quote:
Originally Posted by Skippii View Post
That's a really good idea, actually.
I wonder if you'd be able to wash your used exhaust packing in your clothes washer.
With some sort of a degreaser, like the stuff No-Toil sells to clean their air filter oil, you might be able to clean and reuse the exhaust packing.
It's pointless because the packing is cheap but more importantly it gets saturated with oil and burns out, robbing you of power and increasing the DB's. Think of how candyfloss shrinks when you eat it and you'll get the idea. I'd hate to drink the water from your town or city.

Pat
__________________
La Moto, c' est une aventure qui mene jusqu' au bout du monde...
Eggsontoast is offline   Reply With Quote
Old 05-29-2011, 05:50 PM   #12
jar944
Studly Adventurer
 
jar944's Avatar
 
Joined: Aug 2010
Location: Chantilly VA
Oddometer: 556
Quote:
Originally Posted by Truckin_Thumper View Post
A motorcycle muffler works exactly like a supressor works on a fire arm.

Figure out how to design them fused, you can make a small fortune.

Angled internals maybe multiplyed X3? figure out a way to stuff packing in each slot, or not.

If they can suppress a .50 or an M4 in burst, or any other full auto (small calibre), a measly engine should be simple. Oh yeah, make it legal for the tax collectors and EPA.

Report back with results




Oh, I can for the life of me pay $1200 to make something louder.
$1200 I want it to wipser
Not really, cans (suppressors) are designed to impede flow and significantly increase back-pressure. They are made to slowly release the gas.

Not a good thing for a engine.
jar944 is online now   Reply With Quote
Old 05-29-2011, 05:55 PM   #13
dirtard
Gnarly Adventurer
 
Joined: Apr 2011
Oddometer: 228
my buddy has been running a 2stroke pipe on his crf450 for a few years with no problems. now how would an exhaust from say a yamaha r1(or any sport bike for that matter) sound on a big single cylinder dirtbike?
dirtard is offline   Reply With Quote
Old 05-29-2011, 06:00 PM   #14
Skippii
Hookers, my lad.
 
Skippii's Avatar
 
Joined: May 2008
Location: Richmond, Va
Oddometer: 6,492
Quote:
Originally Posted by dirtard View Post
my buddy has been running a 2stroke pipe on his crf450 for a few years with no problems. now how would an exhaust from say a yamaha r1(or any sport bike for that matter) sound on a big single cylinder dirtbike?
A stocker? It would work fine and weigh like 30 pounds....what were you hoping to improve?
__________________
"Umm be careful what you say, this is Skippii....
You may get it delivered in the form of a shake or some interperative dance routine that involves nakedness, pizza and a stuffed raccoon..." -DCrider
Skippii is offline   Reply With Quote
Old 05-29-2011, 06:40 PM   #15
dirtard
Gnarly Adventurer
 
Joined: Apr 2011
Oddometer: 228
Quote:
Originally Posted by Skippii View Post
A stocker? It would work fine and weigh like 30 pounds....what were you hoping to improve?

not nessisarily stock, although some stockers are pretty light. im tryin to get my xr650r queiter with good flow and sound different than anyone elses
dirtard is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 03:42 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014