currently, we've been getting bgf motors that run really rich - need to drop the needle down to the leanest setting to have any chance to get an idle out of them, and then it will still 4-stroke quite a bit
no idea yet what's causing this & since we get them as complete kits, we were thinking bad carb jets, but could be something in the motor
if this doesn't help, be sure to blow thru your muffler to see if it's clear