Expansion Chamber Exhaust

Discussion in 'Performance Mods' started by jhendrix, Jan 25, 2011.

  1. jhendrix

    jhendrix New Member

    I was wondering how people feel about these, i was looking at the one that SBP sells and am curious if it is worth the money and if it is an easy install. Any help is appreciated

  2. gothicguy64

    gothicguy64 Member


    think of it this way the stock pipe works but do racing 2 stroke bikes use stock .

    depending on ur motor size u have to cut a small copper tube to fine tune and its dead easy to fit .

    my motor is only a 48cc but it is fully worked an now i have a heep of sbp bits .

    motor= rse hp1 but made to hp2.5 specs
    sbp = shiftkit, exhaust , low profile filter, metal throttle , rocker kill switch , hix
    plug , 2 inch front mount and a wider sealed bottom bracket .

    when i got my bike it went 65 kph after 600 km i am now hoping on going even faster but i now need fuel line ,jb weld,plus a saw to cut tube to tune
    ohh i forgot these motors are all orig russian m21,s (2 strokes) but good luck finding a m21 ,one went on sale 4 yrs ago and sold for more than 1000.

  3. jhendrix

    jhendrix New Member

    ok so my motor is 66cc and i've upgraded the carb and air filter so what kind of exhaust do you recommend?
  4. retromike3

    retromike3 Member

    I really like S.B.P. tuned pipe

    When I put the pipe on my old motor It was like a adding a supercharger. My bike could now go up the same hills I used have to pedal without having to pedal at all. It made a major difference right away. Nothing else I have done has made such a dramatic change in the performance.

    I did note that my gas milage did go down a bit but the increase in power makes up for that loss.

    It did take me a while to get it "tuned" correctly. I started by cutting a very small part of the copper pipe that connects the block to the first part of the pipe in order to get the power band right were I wanted it,so I never took more than a sixteenth of a inch off at a time.

    One of the effects of the pipe is that the power band is a much smaller area than the stock pipe, but with that much more" bang" its worth the sacrifice.

    I broke a motor mount on my old engine so when I went to reinstall my pipe I had to replace the copper tube that went from the block to the first part of the pipe because it had melted. It cost me a grand total of two dollars and thirty cents to replace it. More expensive than that was the new set of heat resistant tubing (about ten bucks) but as far as I am concerned the total price of that pipe is worth its wait in gold.

    Last edited: Jan 25, 2011
  5. gothicguy64

    gothicguy64 Member

    hey mike what size motor u using and how much u cut off ur tube to tune it ?

  6. jhendrix

    jhendrix New Member

    That sounds awesome and exactly like what i want, im not to sure what you mean about the powerband and how do you know when it it "tuned"
  7. gothicguy64

    gothicguy64 Member

    ok its time u went to sick bike parts and asked the pros .