when messing about with jetting on an engine you need some way of monitoring the air fuel ratio (AFR) . An engine will run even if the AFR is out a bit but you will not get the best performance / smoothness . If its a stock bike leave the stock jets in . Checking plug colour is a load of old rubbish . Also there shouldn't be much fuel in the air box . You should be able to leave the fuel tap on for say an afternoon and the carbs not flood . My turbo charged bandit pops quite badly on the overrun but is set up spot on . Many hours have been spent running round with data logging equipment attached to the bike checking the air fuel ratio .
