it seems that when my engine gets warm, the butterfly in the carb starts to bind. what might be causing that?

thanks

rome

Loosen and retorque the carb body bolts.

would that be the carb screw?

That would be the four screws that hold the cab body to the engine case. I only suggest that because I had an engine that exhibited the same issue and it was due to uneven torque of the bolts.

i think i got that, its nice and loose now. but i notice bubble starts to appear on the fuel line the line that goes to the carb

A few little air bubbles in that line, especially at or around idle, are normal. a lot of big air bubbles or bubbles that do not go away at higher RPM are not normal.