this is exactly why,i do a smoke test,,im a smoker,,,so it dosent bother me,,what i do is block the carb inlet with my palm ,, rotate the piston so it dosent block the port and blow smoke into the exhaust port,either that or  just use air and soapy water,,it will bubble where ever theres a leak,,but back to the carb,,,they are notorious for going bad when left to set up a while,,and different additives in gas will accelrate the drying out or hardenining of the rubber flappers  and the rubber tip om the metrering neddle located under the diaphragm.ps im no expert,but have been around for more than a minute....