I have the Australian , Canadian wr400-99 which was running great untill I started tinkering with it. Now I have two problem spots with my jetting. I,ve spent big $$$ on jets & neddles & now I must ask for help. PLEASE PLEASE PLEASE. I opened up the hole in the end of the muffler from 3/4 inch to 1 1/2 inchs. Now I have a stumble when I snap the throttle open from the closed position. I also have a flat spot at half throttle. I ride at less than 1000ft. My current settings are, DRM#3 160main jet,200main air jet,#45pilot jet,#75 pilot air jet,#62starter jet, 1 1/4 turns pilot screw, wr timed, air box lid off, PLEASE PLEASE PLEASE I don't want to pull the carby apart again. I'm mostly after strong mid range & bottem end for single line trails & snotty hills.