Power Tuning - Ignition Timing
On a mechanically sound GS /EFE engine, optimize the ignition timing before playing with the carbs. Even if the carb's jetting is off, you'll never find the solution until the Ignition Timing is right.
The centrifugal advance curve should start around 1,800 rpm and be all in by 3,500 rpm. Advancing the timing until the engine pings / detonates, then backing off the igniton timing, doesn't always produce the best horsepower. Try advancing and retarding the timing in 2-degree increments to see if your bike speeds up or slows down.
As a general rule 4-valve normally aspirated GS / EFE engines perform best at seal level conditions with 32 to 34 degrees of total igniton advance. Altitudes above 1,500ft, 36 degress total ignition advance is required for optimum performance.
2-valve GS engines perform best at seal level conditions with 36 to 38 degrees of total igniton. Altitudes above 1,500ft, 40 degress total ingnition advance is required for optimum performance.
High-output aftermarket electronic ignitions, are usually a good compromise between getting a strong spark and preserving coil longevity.
Hard-running street bikes may benefit from going to a spark plug that's one step colder than stock but check for evidence of spark plug fouling.