I had to adjust everything on my carb , low speed , high speed , idle . I even moved one of the stops on the linkage a little to get the idle and brakes how I like them. Mine was so tight when I got it that it siezed up when I started it. I had to remove the head and cycle it with the cylinder loose to get it going. After a few head aches its running really good. Mine does not like low nitro fuel at all. It runs really good off 1/2A fuel - 25% nitro 20% oil. A little messy out the pipe though. I ran some 10% Traxxas today , and what a pig !! You can tune it to idle , rev up , just totally gutless!!