Some additional data:
Racing on the Cheap - scroll down to "The Nuts and Bolts" section, note: "close to perfect" is with full AreaP exhaust and factory jetting. Willow Springs is ~2400ft above sea-level, hence main-jet reduction to 95 instead of usual 96
Dyno testing - lean mid-range only - thinned needle to correct.
Racing Order - Dyno testing
Note that factory jetting is both too lean AND too rich. You want to use smaller mains to fix high-end richness. Then unscrew pilot and shim needles to fix mid-range lean. Actually better to reshape needles on mini-lathe to make more gradual taper rather than factory stepped design.
I'm in my second season of racing 250 as Expert; it's extremely competitive due to limited mods allowed. EVERYONE has optimized their bike given allowed mods: exhaust and jetting is free (i should've bought stock in 96 jets). If you've got some new configuration that's even more powerful and repeable on dyno, i'd gladly pay you consult and exclusivity fee of $10k. Hell, make that $20k, i want to beat those bastards!