have you adjusted the mixture screw to get it running sweet?
have you checked it for air leaks on the intake side ?
start the bike and spray some carby cleaner or wd40 etc on all the joins on the carby, and manifold etc
if the idle changes in any way when you are doing it, then there is a vacuum leak that needs to be fixed.
check the valve clearances too while your at it, they'll need adjusting
and are you running an NGK spark plug ?