Home Forums TaG Rotax Max No bottom end power

This topic contains 4 replies, has 3 voices, and was last updated by  Bruce Woodrow 2 years, 8 months ago.

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  • #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

    #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 / tony kart / rotax / kt100

    #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

    #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

    #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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