I know exactly what is going on (hopefully there's nothing else). That screw on the muffler side should actually be FULLY tightened in (no hard necessairly but full in). I put another post about it earlier, but it's a little decieving if you've seen other nitro engines. Most nitro engines have a screw there (as this one does too) BUT there is no screw on the throttle side (where the rubber flange is). On this one there is also a screw on the rubber flange side, but you only want to adjust the one on the rubber flange. The one on the muffler side should be in (to reitterate)
I'm not sure how many turns out the screw on the flange side should be but I"ll check into it later if you need help on that.
What's going on is the low speed adjustment is way to rich but it doesn't necissairly give you audible ques like the HSN does.
Reset your settings (idle is probably fine). Main needle (HiSpeedNeedle) Turn in all the way (not overly hard) and then back out to about 3 turns.
The LSN turn in all the way and try about 1 1/2 to 2 turns out.
If you need to know for sure what mine is at let mek now and I will check it for you.
Let us know if this was it. ALso - how is the buggy preforming for you overall
There are no general rules for how many turns to adjust the carburetor needles to. It can change several times in the course of a day. There are many factors that influence tuning like temperature, weather (sunny or overcast), atmospheric pressure, elevation, humidity, fuel type, plug type, how clean the air filter is and probably a million others.
The best thing you can do if you are new to tuning is pick up an infared temperature gauge (can be had for as little as $20.00) and use it to help get your engine properly tuned. Here is a link (once you have the gauge) on how to tune your engine:
EDIT: That link has a rather abbreviated version of the process. If you are not sure what adjusting the screws does here is an easy way to look at it:
Clockwise = leaner = more air, less fuel = hotter
Counter Clockwise = richer = less air, more fuel = cooler
Your high speed needle is the one that makes the biggest changes to engine temperature. Adjusting this clockwise will cause the temperature to go up, and adjusting it counter clockwise will cause the temperature to go down.
For the step that talks of pinching the fuel line, you want to adjust the low speed needle clockwise to make the engine die sooner, and counter clockwise to make the engine die later.
EDIT AGAIN: For the idle adjustment, adjusting the screw clockwise will increase the idle, and counter clockwise will decrease the idle. You will probably notice that when making changes to the low speed needle, it will often change the idle, and require you to adjust the idle screw as well.