No bottom end power

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    • March 30, 2015 at 12:12 pm #45076
      Aaron Smeenk
      Participant

      I have an older rotax (not sure how old but old style clutch). I’m basically running the jetting that we were told to run at the track, and the clip position we were told to run. I don’t really know much about the adjustment screws though.

      the problem is that coming out of the corners it basically falls on its face and sometimes tries cutting out. when I’m occasionally on the track with other people I can tell they almost rear end me coming out of the corners even when it doesn’t try cutting out.

      we rebuilt the carb and found that the idle jet was originally plugged and rebuilt the engine with no fix. also the original people helping me with the rotax have disappeared and everyone at my track now speaks Portuguese.

      any ideas would be appreciated
      thanks

    • March 30, 2015 at 6:23 pm #45084
      tony zambos
      Participant

      Aaron,
      Just because you’re using the jetting other people told you to use does not equate to having the proper jetting, unless you have the same weight floats, at the same height as the other people. Pull the plug and check its color and also check the color of the exhaust header. Also check the packing in the exhaust pipe.
      With a Rotax, you can’t slam the gas pedal down coming out of a turn. Other causes could be the wrong gearing or maybe it’s time for a rebuild

      LAD Specialties customer / tony kart / rotax / kt100

    • March 31, 2015 at 8:46 am #45122
      Bruce Woodrow
      Participant

      Aaron,

      Also, assuming that you running a ‘senior’ engine – check the power valve. If the power valve is stuck open, the bottom end power will be terrible and then be OK from about 7500rpm up.

      Bruce

    • March 31, 2015 at 9:51 am #45132
      Aaron Smeenk
      Participant

      Bruce,

      That’s one thing we’ve thought about and after we did the rebuild we cleaned the power valve blade off. I’m not sure how to check if its working correctly though.  I do feel like the kart has great top end power though

    • April 2, 2015 at 6:22 am #45281
      Bruce Woodrow
      Participant

      Aaron,

      Once you have made sure that the power valve is moving freely, you can check that it is closing by removing the exhaust from the cylinder ‘socket’ and looking in through the exhaust port – the blade of the valve should close off quite a lot of the port and be pretty close to the piston when the power valve cover and spring are fitted.

      Bruce

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