Since I'm the unofficial aircraft mechanic for Sun_Kissed_Girl's planes, I have brought it upon myself to also fix a problem with her Hangar 9 Twist 3D. Its kind of an odd problem, in which when the prop is flipped (to start the engine), the carb closes progressivley until it is completely shut. It closes about 1/16 of an inch every flip. I cannot seem to find the source of the problem as I've checked the pushrod, the pushrod tube (which is glued in), the carb barrel, the linkage where the pushrod connects to the servo horn, everything I can think of. The only idea I have at this point is that there is some radio conflict between the JR 537 servo thats being used for throttle, and the S3004s that are throughout the rest of the plane, although none of the other servos show any problems. Any ideas? [sm=confused.gif]

ideas? Yeah, when you have a servo that isn't working right, swap it out.

That throttle servo is supposed to hold it's position. It isn't. It's the first thing to suspect. Swap a good one in and see if it's actually the servo or something else. Go from there.

Okay, I'll try that. Thanks.

what engine is it? had an os 45 fsr that the throttle arm was pressed onto the carb barrel and it was not pressed enough for a tight fit and the arm would spin on the barrel,if your carb has a pressed on arm and a spring to help rotate the barrel ,a loose fitting arm in conjunction with the spring would do what you describe

Check The Screw That Holds The Arm To The Throttel Barrel.