Sounds like a fuel problem,maybe too lean when under a load. I would clean carb and try it again.You could try choking it as you throttle up if it stays running most likely fuel starvation. Good Luck RandyI just got a rotax 447 and it will run like a champ without the prop but will stall when i give it gas when the prop is on it. can anyone help?
We had a boat with a 2 stroke that had a fuel burn that all of a sudden went crazy... we were fueling it up every other day.... Thought there was something seriously wrong with our motor... but then we noticed the neighbors car smoking and put two and two together.