i have a new sbp exhaust on my 66cc chinese bike. now its sluggish in the top end

Discussion in 'Performance Mods' started by brandenclrk, Dec 13, 2010.

  1. brandenclrk

    brandenclrk New Member

    i have a new sbp expansion chamber exhaust on my 66cc chinese engine. now its sluggish in the top end. not as fast as it was before. what do i need to do? adjust carb or maybe a higher flow air filter?
     

  2. 5-7HEAVEN

    5-7HEAVEN Guest

  3. Ghost0

    Ghost0 Guest

    First read the instructions, it details how to tune the carb and the pipe. First is check your plug. Typically the top end falls flat for 2 reasons, too rich at top end and too long of a pipe header. Again read and follow the instructions as it details these tuning options.
     
  4. motorpsycho

    motorpsycho Active Member

    I disagree with you because normally if an engine goes flat or bogs on the top end, it's because it's too lean.
    when you put an expansion chamber on, or a high flowing exhaust the engine will run leaner.
     
  5. Ghost0

    Ghost0 Guest

    Too rich or too lean will do the same thing but typically these things are over jetted which is why I recommended checking for a too rich condition to start. Only the plug will tell the true story.
     
  6. motorpsycho

    motorpsycho Active Member

    that's odd because i had to richen my engine to get it to run right. going from the stock
    .70 jet to a .74 jet got rid of my top end bog big time, I even picked up about 3 mph by re-jetting it richer.
    no, i don;t have an air leak, and my plug is a nice tan color now.
    with the .70 jet my plug was a silvery color, which indicates that it's too lean.
    I live in the midwest U.S.A. and I did this when the outside air temp was in the mid 80's.
    my engine has a long pipe with a modified stock muffler (no expansion chamber) and a velocity stack with a high flow k&n style filter inside it.

    normally if a 2 stroke is too rich you will experience 4 stroking on the top end, which is totally different than a bog.
     
    Last edited: Dec 14, 2010
  7. brandenclrk

    brandenclrk New Member

    Just got home from work and checked my plug

    My plug is a dry fluffy dark color. Pretty sure it means too rich. Tomorrow im gonna check the air filter. I'd like to have some instructions for tuning my carb and pipe but i only have motor installation instructions that came with carb/motor kit and no tuning instructions. Just got my pipe in mail the other morning and it didn't have any kind of tuning instructions or paperwork whatsoever. If anyone knows how lemme know. I really appreciate your feedback. Learning alot from forum pages.
     
  8. brandenclrk

    brandenclrk New Member

    ok i couldnt wait. i pulled off air filter and it had gas on it. what could the prob/solution be.
     
  9. Pablo

    Pablo Motored Bikes Sponsor

  10. brandenclrk

    brandenclrk New Member

    I bought it from sickbikeparts.com

    It came with some bubble wrap, some bubble gum and some appleheads.
     
  11. Pablo

    Pablo Motored Bikes Sponsor


    ????
     
  12. motorpsycho

    motorpsycho Active Member

    it's normal for these engines to spit gas back out of the carb and into the air filter because there are no reed valves. reed valves are one way valves that go in the intake port. they allow gas and air to get into the engine, but they will not let the gas get spit back out into the carb and filter.
     
  13. brandenclrk

    brandenclrk New Member

    yea, just the expansion chamber and some candy.

    yea just the sbp expansion chamber and some candy. I ordered it from www.piratecycles1.com. Oh yea they also sent one of their stickers with their logo and some business cards. Sticker ain't goin' on my bike now. Sad thing is it was my first time buying from them and I would've probably ordered more parts if they didn't leave me hangin with no instructions whatsoever.
     
  14. Ghost0

    Ghost0 Guest

Loading...