Check your needle settings on the Mach Carb, the Low speed needle on the side of the carb should be set to about 2 turns out and the Hi speed should be set to about 3 turns out for starters and tune to preference from there. You also may have trash in the carb especially if you dont run a fuel filter. I was also wondering if you ever race at K&M in New Caney or FasTrak in Houston. I was at the Bayou City Classic at FasTrak in Houston this past weekend. There was some awesome racing goin on! Got to talk shop with Adam Drake (very nice guy). I'll probably be at K&M weekend after next to race my XXX NT. I have to order a new enging since the rear bearing came apart in mine this past weekend. I couldnt race because I forgot my backup engine and box with parts at home =(. Probably going to be ordering an RB X-12 Turbo or a Sirio .12 Turbo.