I have just restored a FZR400RR Race bike that has been in storage for the last 12 years. Bike was built up as a full race bike from new in 1990, and is heavily modified. (Ported Head, Cam, 1mm oversize forged pistons, velocity stack airbox, full race exhaust, total loss ignition etc)

I have stripped down and cleaned the carbs. Bike starts instantly and runs fine from idle to about 6k, then has a large "flat spot" not really a miss, that lasts to about 8k. Past 8k it is very powerful and rockets up to the 14k red line.
It's almost like a 1970's 2 stoke power band.

Does this sound like carburation or more likely CDI.
If CDI what are the Chinese CDI's like? I can get them delivered for US$100....

From 6 to 8 .... it could be the transition from idle jet to mains or that the exhaust is a smidge large for the bike, I assume you don't have an exup and 8k is where the exup would be fully open which is why it goes well at top end.

Your best course is to have it dyno'd which should point you in the direction of either electrics or fuel. CDI's are quite robust and I'd say if yours was duff the bike probably wouldn't run at all. To me it sounds more like set up.

Thanks for your helpful reply. I will strip the carbs again and check for emulsion tube wear, and failing that book it in for a Dyno session.

Sorry I can't be more help