Glad you found the problem with your engine. IF your plane is coupling towards the belly, or gear, that is normal. What I did was to make a mix that gave the plane slight up elevator when the rudder was applied. This took the coupling out. On the Futaba 7 CAP and 9 CAF it's a P-Mix with the rudder as the master and the elevator as the slave. You can either put it on a switch on have it stay on all of the time. Mine is on a switch. You can also do a second one, on the same switch, to add in slight aileron at the same time to hold it rock solid in the knife edge. Isn't technology wonderful??? Sorry but I can't help you with the smoke thing, never ran any.