Not so happy so far. My 2-stroke thinks it's a 4-stroke.

Discussion in '2-Stroke Engines' started by Sprocket777, Aug 1, 2009.

  1. Sprocket777

    Sprocket777 New Member

    So how do I teach my 2-stroke to stop acting like a 4-stroke?

    I have a 47cc dax kit. It's basically new with about 38 miles on it, but it will only carry me to 23 mph with a 41 tooth sprocket. Some times, when all luck happens, it will 2-stroke for a split second. Then it goes right back to sputtering.

    It has somewhere around a 25:1 mix (about a third of it synthetic), no air leaks, ngk plug gapped around 22, plug color is medium to dark gray all over. The muffler has been de-catted and has two 1/4" holes added to the baffle. Carb needle is on the second to leanest setting. I live at 936 feet elevation.

    Is this to be expected? I'm sadly disappointed after what I have read about average experiences. Maybe I should've got a 4 stroke?

    Either way, riding a MB is sweet. I have a Vstrom too, but this is fun in it's own way. Thanks for the help.



    DJEEPER Member

    Make sure your carb is all the way on the manifold.

    Check compression?

    Old gas? Try putting some nitro in there....just a small bit...or get a new oil/gas source.

    I would say give it time to break in...and be easy on her. these things take time and patience...dont try to break any speed records until you hit about 500 miles or so...
  3. arceeguy

    arceeguy Active Member

    Sounds like you'll need to rejet the carburetor for your altitude. Some have had good luck with soldering and re-drilling. You may also want to try lowering the float level 1 or 2 mm (1 mm at a time) to lean out the overall mixture a little. Be sure to take a base measurement before you bend the tangs, so you can return it if it gets worse.
  4. Sprocket777

    Sprocket777 New Member

    Thanks. Carb is on there and sealed with rtv. Gas is shell 87 oct. Unfortunately i haven't been going very easy on her. Last night I did full throttle for about 5 minutes so I could get a good plug reading.

    I agree with the thought that it's a bit rich. What do you think about running it without the airbox just to see if it helps a bit before I take the time to mess with the carb?

    DJEEPER Member

    i think you need to stop with the high speed runs until you get her broken in!!!

    this is the best way to kill a motor...
  6. arceeguy

    arceeguy Active Member

    If it sounds rough throughout the entire throttle and RPM range, drop the needle to the leanest position and retry. If it is still rich, lower the float a little. If this doesn't work, you'll need to mess with the main jet.

    I would not run without he air cleaner as the intake is in direct line of debris tossed up from the rear tire. A little sand in your crankcase will kil your engine in short order!

    As far as breaking it in gently, I personally don't think it matters as long as the fuel mixture isn't too lean. Too rich of a mixture will keep combustion temps down, and may help with the additional oil delivered in the fuel.