The new motor is mounted to an Exmark 60 turf tracer. Something is not happy with this brand new motor. It has 5.5 hrs on it. I idle it all the way down and leave it there for 30 sec and it still lets out a backfire. I believe the throttle cable is adjusted well. When all the way in "rabbit" the throttle lever seems to bottom out against a screw and plate. But, maybe when in "turtle" is should idle down even more. I have to adjust the choke cable. The motor is a CV680-3089. Any ideas?