Engine Trouble Full Throttle and engine just took off

Discussion in '2-Stroke Engines' started by atomichurley, Jan 20, 2012.

  1. atomichurley

    atomichurley Member

    ok guys i have been riding my bike around for a few weeks now but today i went for a ride then i went to this oval concrete track today and was taking my bike around there at full throttle....then she just came to life like revved to like 10k the whole engine tone changed and i was going so dam fast like i have never been before then after about 30 secs of riding like this the engine started to die :icon_cry: i could restart the bike but it wouldn't run for very long and wouldnt even idle with the clutch in so i finally got home after the bike surging power the whole way home (engine being powerful then weak) and i left it for a few hours and went for a ride and the bike ran normally even with holding full throttle for a while. So guys my questions are what caused this massive power gain and how do i get it to run like that all the time without any trouble and why did my bike run normally after i let it sit for an hour or two? :thinking:

  2. toojung2die

    toojung2die Member

    Quick guess, a little piece of debris in the carb float bowl found the main jet and leaned it out. After sitting awhile the debris dislodged and is back in the float bowl waiting for it's next opportunity. Your profile photo shows you have an in-line fuel filter but it looks like it may be installed backwards.
  3. motorpsycho

    motorpsycho Active Member

    yep, sounds to me like it was leaning out.
    either junk in the float bowl . main jet, the float is getting stuck and allowing the float bowl to almost run out of gas, and then getting unstuck to let the bowl re-fill OR your intake gasket is developing an air leak.
    yes, the gaskets can leak and then not leak due to temp changes.
    the stock gaskets are junk...and are just paper that will get wet from fuel and then dried from the engine heat.
    wet, dry, wet, dry...this will cause the intake gasket to fail and leak.
  4. jaguar

    jaguar Well-Known Member

    you had a mini-seizure and you definitely need to take it apart and use sandpaper to take the aluminum off the cylinder. Otherwise you will groove the rings which causes compression loss (and power loss) eventually.
    Why it ran like a bat out of **** I dont know. could be your stock CDI was like mine and sometimes advanced with rpms and sometimes not.
  5. gothicguy64

    gothicguy64 Member


    nice rse motor i see with that unipod ...

    all u need now to fully awken that motor is a sbp shifhtkit an sbp expansion pipe ..

    i have both on my rse hp1.5 48cc motor but ive killed my rse shaft bike rear wheel .....

    top of 64 kph with stock(lol)rse bits ....much much better with sbp bits an no longer revs out at same 60 khp ...:whistling:

    bike is a cell mtx2 dual disk an a chrissy gift of 450 bux

  6. Bighat

    Bighat New Member

    float pin unscrewed?

    This sounds similar to my first build experience. The problem was that the speed carb used was sent to me with the float pin unscrewed or it vibrated loose. Ran at full throttle and the only way to slow her down was to press the kill button.
  7. motorpsycho

    motorpsycho Active Member

    see the picture below. circled in blue is the float pin.(from a generic carb, but the idea is the same)
    you will notice that the float pin (circled in blue) does not screw into the carb.
    as i said in another post, the only 2 things that screw into the carb inside the float bowl is the main jet, and the needle & seat.
    what are you referring to when you say "float pin"? I don;t think you are naming the right part.
  8. Bighat

    Bighat New Member

    The long brass piece on the right.

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