fuel screw--can it make this much of an impact?

Yesterday after I put in the 155 main jet, I took my quad to an open field where I could open it up in 5th gear all the way. It seemed to be fine I haven't looked at the plug yet. I took the airbox lid off when I did this. As I rode it, it seemed like it took a while to get to top speed, and when it gets to top speed it seems like it can go faster put it won't like it needs more gas. I am currently running 155mj-38piolt, stock needle groove. So today I gave the fuel screw about 2 turns. I then went back to the same field I went to yesterday. I still have the lid off. I ran it and I can now hit the rev limiter in 5th gear wide open. I have the 15 tooth sprokcet on the front. What does this mean? Did I turn the fuel screw to much? I was about to go buy a 158 main jet and cut up my air box. Any help would be great thanks.

bump

[CranMan]

I don't know for sure...but I don't think the fuel/air screw has anything to do with wide open throttle. I'm pretty sure that's just your main jet. I think in the EX Tech section there's a article that covers which part of the carb relates to different throttle positions..

turning out the fuel screw will mainly help with cold starting. maybe the temp was different of the humidity. I found raising the needle 1 notch really helped me get up to speed quick. the 155 may be a bit lean with no lid, but try raising the needle a notch. you'll notice the mid-range punch difference.