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