kwiknik.......when you get your nitro vehicle, whatever it may be there will be detailed instructions on how to break in and tune your nitro engine.......It is really a simple procedure but seems to have been turned into something only the "Nitro Gods" could perform successfully..........NOT TRUE !!!
First off to lean an engines carb is to reduce the supply of fuel by turning the high speed needle inward (clockwise) ....to richen the carb is to increase the fuel supply by turning the high speed needle outward (counter clockwise)......Just like the outside water faucet, turn it left...more water, turn it right less water....
You will want to run it rich for the prescribed number of tanks of fuel for break in (covered in your instructions) then when it is time to lean it out for better performance you will only do this in small amounts at a time...think of your high speed needle as a clock face with the hour marks around it.....12 is the top 3 is 1/4 turn to the right 9 is 1/4 turn to the left and 6 is 1/2 turn from 12. When you start to lean your engine only do it in one hour steps ( let's say from 12 to 1, then run the car and see if it goes faster then turn it in again same amount inward .....keep this up until it either doesn't improve or quits smoking at this point stop leaning it any further, and to keep it running cool enough richen it buy about 2 hour marks, but in any event make sure you see a fair smoke trail.