$65 expansion muffler

Discussion in 'Performance Mods' started by crowvise, Aug 17, 2010.

  1. crowvise

    crowvise Member

    Is this model louder, quieter, or the same decibel level compared to stock? If so, by how much? How much more speed? What exactly are the operational principles of how it affects engine performance? Oh, and if anyone has an end cap for a stock muffler or a stock muffler they don't need i am willing to be a charity case.
    Last edited: Aug 17, 2010

  2. GearNut

    GearNut Active Member

  3. crowvise

    crowvise Member

    i thought that the smb is a muffler. So the stock muffler goes inside it? What is the most quiet one no the market? Is there a performance tradeoff for lower decibels?
  4. GearNut

    GearNut Active Member

    Unless I am totally misunderstanding you, there is the expansion chamber portion of the exhaust system which improves performance, and then there is the muffler, which keeps your neighbors happy.
    A good flowing muffler will not negatively affect performance. A restrictive muffler will.

    Referring to the wiki link, the muffler would attach to the stinger part of the exhaust.

    Do you have a link to this $65 exhaust?
  5. I have a SBP expansion exhaust comming late this week, or early next week. Can give you more details then. :)
  6. crowvise

    crowvise Member

    I thought the entire exhaust is the muffler. I told you I don't know :poop: about engines. It is difficult for me to articulate correctly on a subject that is new to me. Sorry. And thank you. Once again your link is phenomenal.
    Pirate cycles and sickbikeparts have it. The SBP expansion kit that Schwinn-Locura is about to procure-a.

    Hey Schwin-Locura I also look foreward to hearing from you after you install yours.
  7. Oh I'm looking forward to it also. I check the mail everyday even knowing it wonn't be here for a little while.
  8. GearNut

    GearNut Active Member

    Do not be sorry! Once upon a time I did not know anything about engines or bicycles either.
    They are fun to learn! :)
  9. I don't know much about bicycle engines either, mostly just applying what I know from other things I built.
  10. wheelbender6

    wheelbender6 Well-Known Member

    I saw a post where a member replaced the missing end piece of his stock exhaust with the end of an aluminum can. He cut one hole for the bolt that holds it in place and a second hole for the exhaust to escape.
  11. Pablo

    Pablo Motored Bikes Sponsor

    Without the optional muffler, it's about the same dB but very different sounding. With the optional muffler after the silencer - it's quieter than stock and a BUNCH more power.
  12. I got my SBP chamber today. I have it tuned for low end power (getting a smaller rear sprocket soon.

    Its amazing, been practising some good wheelies. The torque is right there, and I still gained on the top end. I have some carb adjustments I need to do but its not bad as is.

    Also for the sound its a little louder, and a bit more dirtbike-ish I guess I'll say it. Its not over the top obnoxious though.
    Last edited: Aug 19, 2010
  13. chainmaker

    chainmaker Member

    I have this exhaust and it kicks it...did You take the time to clean up the exhaust manifold and manifold gasket ??
  14. Yeah I did. Also check your intake, Mine had some casting problems.

    I only got to drive it for 1 day then my CDI went for some reason. Waiting on a new one in the mail right now. Also put on my Boost Bottle, and have a carb in the mail.
  15. chainmaker

    chainmaker Member

    I cleaned up both with a small hand file took a bit of time ..Im using the stock carb and a 39 tooth sprocket and Its got enough oomph for Me.
  16. namefail

    namefail New Member

    i ordered an expansion chamber from Boost Bottle Industries 16 days ago via pay pal. Have no conformation of shipment and no tracking information. Still havent received my item. He ha also been dodging my e-mails. Prolly be out 85 dollars. Avoid this guy


    *ill update this if i receive my product. still a **** dealer tho
  17. gd925

    gd925 New Member

    regarding the email dodger

    I'd prolly dispute that via your bank or paypal and report him to the Federal Trade Comission thats what I did when I got ripped by CopacabanaBikes, don't ever buy from them by the way.
  18. the expansion chamber is the main part. that does little to muffle any noise. it is there to boost the power of the engine. it acts as a power boost because of its shape, when the exhaust gases to through it, some bounces back into the cumbustion chamber. it comes included with a "silencer" which you put on at the end of the expansion chamber. that is what will quiet it down some. then sick bike parts also sells another muffler that can attach to the silencer. so it kinda acts as 2 mufflers if you have both hooked onto the expansion chamber. they say it doesnt effect performance... i have not tried one of these expansion chambers. i am new to motorized bikes. i bought my first kit (sd stinger) in december. and have been having fun riding, fixing and leaning about them. i also work on cars (mostly classic chryslers) so i know a bit about mechanics, and how engines and other systems operate. although for me it is sometimes more fun to ride and fix my motorized bike, because its alot less stressful when something goes wrong...

    i havent gotten alot of the after market performance parts yet. i have gotten the billet intake. which seems to make the engine rev alot cleaner. i also got the teflon coated clutch cable. which is AWESOME. also have a set of those dellorto jets for the carb. and i have the pirate cycles hub adapter with a 40 tooth sprocket. i really like that too. because you can actually get your chain tension even and the sprocket straight. plus im sure it makes the rim last alot longer. i also use an after market wire and spark plug. so i havent really gotten into the parts for the engine itself. like the higher compression heads, the expansion chamber exhaust, the dellorto, or cns carbs... havent done the porting to the engine like some people talk about. i will get to all that eventually..

    i would imagine that the expansion chambers do help with power. of corse like everything, it will work best after it has been tuned. and once you have the carb jetted perfect, the air flow just right, and the expansion chamber at the right length. im sure you can really fly! if you go on youtube you can watch some videos of people who have the sick bike parts expansion chamber on, and see what it sounds like. i dont think its any louder than the stock exhaust. and it seems to sound a little deeper. and im sure if you have the silencer AND the muffler on it, it would be quieter. its nice to have a quiet engine. but you can usually only get an engine so quiet before it starts to effect performance...