I'd like to know if the expansion chamber is a waste of time.

Discussion in 'General Questions' started by sully1617, Apr 22, 2016.

  1. sully1617

    sully1617 Guest

    what do you think? from what iv'e read most of the add ons are just eye candy and don't really help to add power, help idle or make the ride go faster. again, what do you think?

  2. wavygravy

    wavygravy New Member

    hi sully if you are refering to the china 2 stoke motors you are correct in asumeing the power mods are a waste of time & money, they are what they are & dont expect much from them, if you want performance get a motorcycle engine with gears, i am one of the origional founding members of this site & have done vast experimentation with bicycle drive trains, have a great day!
  3. Greg58

    Greg58 Member

    I disagree, a engine properly tuned to a expansion chamber is the "best upgrade available". If you can fabricate get a KTM or Yamaha pipe from a 60-85cc and adapt it, you will be surprised. Look at the pictures of all the race bikes, they don't run expansion chambers for "looks".
    Timbone likes this.
  4. KCvale

    KCvale Motorized Bicycle Vendor

    I guess we differ in opinion gravy...
    I find a properly tuned expansion chamber exhaust to the be THE BEST performance enhancement for a 2-stroke ever made.
    I'm talk ~ 1/2 a HP increase.
    It's like a reverse Turbo Charger and work like this...


    If you want to see my pros and cons for 2-stroke performance enhancements look here.

    Far from thorough but based on first hand knowledge over the years of building.
    Hope it helps.
  5. Greg58

    Greg58 Member

    Great guide KC.
  6. HeadSmess

    HeadSmess Well-Known Member

    the tuned pipe, a properly made and designed one (not cheap ebay ripoffs that have no design at all) is the one biggest improvement you can make to any twostroke engine.

    when you can get a 2hp chainsaw engine to produce up to 7hp simply by making a pipe and doing nothing else AT ALL...

    ever watched the hotsaws? those big fat exhausts must just be eye candy and do nothing... silly people!

    and i have no idea why they would bother putting them on virtually any motorcycle manufactured after the 70's...
    Greg58 likes this.
  7. sully1617

    sully1617 Guest

    what brand or website should i look to? i'm using a diamond frame with a grubee 66cc
  8. sully1617

    sully1617 Guest

    what brand or website do you recommend? i'm using a 66cc grubee on a diamond frame
  9. HeadSmess

    HeadSmess Well-Known Member

    having never purchased one, but always making them..no idea.

    plenty of threads with links to decent ones.
  10. jaguar

    jaguar Well-Known Member

    the only one I recommend is my own design, the torque pipe. Click on my signature link to read about it.

    the ones sold for the chinese engine are way too loud (the belly stinger design of my pipe makes it quiet) and they reduce power at RPM just below the pipe powerband.
  11. butre

    butre Well-Known Member

    I just put a sound level meter up to my own design, and at 3 feet wide open throttle it maxes out at 83 decibels. there's no belly stinger, but the stinger is placed 4 inches into the pipe.

    83 decibels is legal in nearly every state. many Harley OEM pipes top out at around 105, which is over 4 times louder than my pipe.

    I plan to make my next exhaust system a belly stinger with end bleed design for fine tuning both volume and chamber pressure.
  12. sully1617

    sully1617 Guest

    i'm confused by your terminology. belly stinger? reduced power below the powerband? help me out here please
  13. KCvale

    KCvale Motorized Bicycle Vendor

    I like the SickBikeParts pipe.
    It is far from easy to install but it sure does a great job.
    For a 66cc with an NGK cutting the short straight copper piece in half tunes up just right.

    What's cool is you can custom fit it to your bike.




    Not easy, but great performance.
  14. 45u

    45u Active Member

  15. gus.

    gus. New Member