Actually the tuning is the other way around, the LSN has no Impact on the HSN but if you lean or richen the HSN the LSN will also have reduced or increased fuel pressure..

If you are running too lean a LSN then the motor can appear lean all over and lean bog...

Set your HSN for clean running over the longest straight (or longer) then set the LSN for a clean pickup...

To check you LSN, pinch the fuel line just before the carb...

if the engine speeds up after a few seconds, races for a bit and then cuts, you were about right...

if the engine just dies you were too lean

if the engine speeds up after a longer period 4-5 seconds, and then cuts you were too rich...