Is it a lot of gas? like is it running out of the air filter in a stream?
or, is the filter just always damp with gas?
it's normal for these 2 strokes to spit some unburned gas out the back of the carb on the exhaust stroke.
if gas is streaming out of the back of the carb, then your float level is set too high and causing the carb. to flood over.
But, normally when that happens, the engine won't run because it's flooding the cylinder as well.