Engine Trouble weird performance change, what to check?

Discussion in '2-Stroke Engines' started by blankbox7, Jun 3, 2012.

  1. blankbox7

    blankbox7 Member

    When out for a cruise on my recently built mbike, there was a stretch where I was around maybe 3/4 throttle for about a minute or two, when suddenly lost all power (kinda like running out of gas, but was not). when I got to my destination I tried starting again, and got it to run, but to have it idle I had to turn the screw all the way in. The rpms were at where it used to be, and it seemed to run fine but with a small difference in power.

    I am clueless as to why this happened, what should I check first, what could be the source? I was thinking maybe a dirty carb, I've had that happen before but the effects were different than this
     

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  2. Sgt. Howard

    Sgt. Howard Member

    Open your gas cap and close it... then see what happens
     
  3. blankbox7

    blankbox7 Member

    That's actually the first thing I did because I checked to see if I just ran out of gas, but no difference as far as I could tell, I'll probably just check over everything. I was just wondering if anyone else encountered this issue, thanks for the reply
     
  4. Greg58

    Greg58 Member

    When you said "recent built " are you still running breakin gas mixture? If so what ratio? You might Have loaded up the plug a little.
     
  5. blankbox7

    blankbox7 Member

    yea still on 16:1 mixture but almost done with it, I'll check the spark plug then its no big deal, but would that have caused it to lose power as suddenly as it did?
     
  6. Greg58

    Greg58 Member

    one thing that happens sometimes is the jet gets loose or falls out into the bowl of the carb. due to vibration.
     
  7. motorpsycho

    motorpsycho Active Member

    make sure that your choke didn't close by itself.
    the other hting that's possible is that your float is stuck and it's causing the carb to flood over.
    based on the angle of your carb, this is possible.
    sometimes, if the carb is at too much of an angle, the fuel level is also at an angle.
    if the float bowl runs almost empty, the float can get wedged in the bowl, causing it to stick.
    the carb needs to be as level as possible so that the float goes up & down on a flat plane.
    if the float tries to go up & down at an angle, it could get wedged in the bowl.
    this happened to me a long time ago on my first build.

    also, like greg58 said, the jet rattling loose and falling out isn't uncommon either.
     
    Last edited: Jun 4, 2012
  8. blankbox7

    blankbox7 Member

    Thanks everyone for the advice, I'll be sure to check the carb asap. Being as tight of a fit as the engine is the carb wouldn't fit right so I flipped the intake tube upside-down, until I can get a hold of one of those Manic mechanic ones that is.
     
  9. 2stroker

    2stroker Banned

    Check your gaskets!
     
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