You did not note the oil mix ratio. That would have helped note the stage the engine may be in, but I think it's still in the early stages of brek in. It's way too early to be messing with springs and such. The transition and mid range will improve as the engine runs a little more but in the meantime try some carb adjustments to improve things. Lean the high needle to peak and back off about 100 rpm. Now lean the low needle to peak and leave it at peak rpm. BTW, do the low needle adjustments at about 2,500 to 3,000 rpm.

Now try the transition. If it's not what you want, work the low needle about 1/16 turn at a time either way to improve. Leaning the low needle too much will always "bog" the engine. Read the post about 'break in time" for a little more info.