Some of the Tower 46 carbs had a sloppy fitting barrel. The air would come in around the throttle lever end of the barrel.
There's been a very large thread going on here about the carb on the GMS 47. It's the same carb except the needle valve is on the carb.
http://www.rcuniverse.com/forum/GMS_...2290854/tm.htm
Read it.
Enjoy,
Jim