Originally posted by InitialD
If you're saying that there is no relation between High speed needle and the rest of the needles (i.e. low speed and middle speed needle), then I would take whatever advise you give with a pinch of salt.
Anyone will tell you that leaning the High speed needle will indeed lean the Low speed needle settings because the main fuel delivery system comes from the High speed needle first. That is the primary reason why you tune the High speed needle before touching the Low speed needle.
To elaborate on your statement. When you lean the Top end needle you also lean the mid end needle and low end needle. This is the main reason people blow plugs. They lean out the top end without readjusting the bottom end (the one that blows the plugs mainly).
When you adjust the mid end needle you also have to adjust the low end needle the same amount. - (ie. - you lean out the mid end 1/8th turn so you have to richen the low end the same amount to keep the proper setting)
This is the main reason most people always set the high end needle first when breaking in an engine. Some people say you should set the low end first but just ask them how many plugs they go through to get the engine running right. Also, when breaking in an engine (and Im sure the resident engine modifiers will agree) its the initial punch of low end that does most damage to a tight engine and not the top end power which would also suggest that you leave the bottom end rich until the engine is running free.