its definetly getting too much air if you can close thechoke and rev it up.
what jet do you have in the carb?
is the airbox attached?
did you add a performance exhaust?
do you have proper fuel flow?
these things can cause the lean situation that youdescribed. an air leak would be found at the intake, and cylinder base gasket. on a tomos engine, the cylinder base gasket can be mounted 4 different ways, but only one way is correct. and if you rebuilt your engine, i'm willing to bet that gasket is on wrong. if so, thats where your air leak is. its hard to see how the gasket needs to be installed, but study it and you will figure it out.