when maxing out in rpms....

Discussion in '2-Stroke Engines' started by superbee, May 4, 2009.

  1. superbee

    superbee Member

    Sorry if this is a dumb question but im pretty new to 2 strokes...

    When your riding along, and you only part throttle, the engine runs choppy.. and when you go wot its smooth..

    My question is, when i max the bike out, (motor cant go any faster) its choppy like it is when its part throttle. Does that mean it cant breath any more air, or does that mean its not getting enough fuel?

    Get what im asking?

  2. 350zdrftr

    350zdrftr Member

    I wonder the same thing , I just got mine running but I can't get it to idle , but it does run rather choppy at part throttle is there anything that can be done to fix this ?
  3. superbee

    superbee Member

    part throttle being choppy should be normal, i was just concerned about the max rpm being choppy.
  4. Junster

    Junster Member

    My engine was the same till I got about a gallon of gas run thru it. It's running way smoother now. At extreme high rpm's it does start to stall I think it's running out of gas. I'm going to leave it that way though. I don't need to rev it that hard.
  5. spad4me

    spad4me Member

    With a cheap carb a happytime will 4 stroke ( fire every other revolution at some speeds) this is normal.
    Unless you want to buy a wallbro carb EXPENSIVE!
  6. arceeguy

    arceeguy Active Member

    "4 stroking" means that the mixture is too rich. (too much fuel)

    You want to avoid a mixture that is too lean. This is death for 2 strokes. An engine that is running too lean will bog down as if it is running out of fuel. (no 4 stroking) If your engine is more powerful at part throttle than it is at full throttle you are in trouble!

    Engine sound comparison:

    Rich: d d d d d d d d d d d d
    Good: waaaaaaaaaaaaaa
    Lean: mmmwwwwwaaaaaaaaaa

    Ok that kinda sucked, but some may get the idea.....

    The HT carbs are very simple and effective for their intended purpose, but it is very difficult to get them to have a consistent mixture over the entire throttle/RPM range. It is possible, but it usually requires re-jetting and fine-tuning the float level.