If an engine is in good shape and the tune is spot on, a cold engine will idle just fine. But preheat your engines everytime. You know the tune is off, if the idle is too high or low before the engine has its operation temperature. Should be able to accelerate rather smoothtly even when its cold.
Lack of power? Many Novarossi owners doesn't lean the HSN enough. It must "sing" on the straight instead of sounding like a sewing machine. After the HSN is spot on, finetune the LSN and then you'll see the power of your engine. Remember SMAAAAALL adjustments (1/12 of a turn or so when you fine tune the engine).
It often feels like the clutch is defective if the engine isn't tuned correct (too early engagement).
Use a 7 mm venturi.
Picco/Nosram venturies doesn't fit a Novarossi engine