no they arent. once you get them dialed in theres nothing to it. i havent done anything to mine and there has been a 20 degree temp change since i tuned it. runs as strong as it did the day i tuned it.
i played with the 40mm keihin and the 44 lectron when i was tuning it and the lectron had more power everywhere than the keihin. they are good carbs, just pricey as fuck.