I,ve got one of them had the same problem the best solution was for me to get another carby from tower hobbies ,the one they sell needs a bit of work on it as they don,t fit you,ll have to get some emery paper and reduce the size of the inlet side of the carby by 40 thou and also the depth it goes into the motor as the throat is to long I cut approx 1/4inch of that ,watch out for the size of silicon tubeing you use, also I had one size on and it wasn,t getting enough fuel increased size of tubing and now its up and away I can pull 12900rpm max and it idles at just over 800rpm,s and all up it cost me $ 38,00 U.S plus postage $10.00 which converts to $70.00 Kiwi
still you don,t get into this hobby/ sport with out you hand in your wallet all the time cheers mate hope this helps