Engine bogging down after mid throttle (installed SBP Expansion chamber)

Discussion in '2-Stroke Engines' started by asfazrq, Oct 18, 2010.

  1. asfazrq

    asfazrq Member

    I have a unique issue. I installed the SBP expansion chamber last week and the engine has running fine I have a few issues:

    1. It has been difficult to start it on colder mornings. I have to constantly pedal with the choke fully open for 30 seconds for it to come alive. it never did that before.

    2. the engine bogs done at mid-throttle even after it warms up. it was doing it slightly when I first installed the kit but now the problem has gotten worse. When I reduce my speed the engine is almost on the verge of shutting down unless a) I pedal a bit b) open the choke until it get some extra speed and then shut it off.

    I had to admit that I remove the exhaust gasket which was included in the original kit which was literally glued to the exhaust outlet so I had to scrape it off. I replaced it with a metal gasket which SBP provides. I was wondering if there is an air leak and was wondering about how I should go about fixing what and where! Please advise and thank you all.

  2. HeadSmess

    HeadSmess Well-Known Member

    too lean.

    try lowering clip on needle two notches. help? it needs bigger jet...

    didnt say what happens if you go wide open throttle... choke or no choke... biggest giveaway cus the choke RICHENS. then you know if you too lean or rich...

    metal gasket? made of what? for an exhaust gasket? um? metal? definitely metal? solid or, like...um...squishy? (graphite)
    Last edited: Oct 19, 2010
  3. Grayling

    Grayling New Member

    this happens to me alot and i have the stock muffler but it just broke so i might upgrade
  4. Lazieboy

    Lazieboy Member

    High rev

    I just started having an issue where when clutch is squeezed in it goes into high rev? but not an issue when engaged and riding. any ideas. Yes i have tried the idle screw no change.
  5. Ghost0

    Ghost0 Guest

    Lazieboy, sounds like an air leak to me. The slow to return to idle or high revving coming back to idle is very typical of an air leak. Check your intake for air leaks. Both the connection to the cylinder and at the carb. Speaking offlline with the OP turned out that was his problem too.

    Yes our pipe comes with an aluminum exhaust gasket. Just need to be sure that both mating surfaces are flat and a little RTV won't hurt just to be sure. Also noet that an exhaust leak will have little to no effect on the lean or rich mixture. This is primarily due to intake leaks.
    Last edited by a moderator: Nov 1, 2010