This may sound like an old re-hash of RCGF engines but I am having a problem I can't find the answer by searching these forums or Google. It may be I am not conducting the right search but so far no answers. A couple days ago I was flying my Flying King with the RCGF 20 and the first flight was great, good power and response. The second flight was going well also until after I had competed my take off and made my turn. I went to reduce throttle since it only requires 25% to fly. The engine would not slow down, I thought the throttle linkage came loose and I would have to stay up until the tank emptied. As I was flying around at 5-6 thousand rpm, I started tinkering with the trim and could bring it down to a fast idle and landed that way.
After getting it back on the start stand I checked everything and all was well, there was nothing loose or binding. Next I checked all the fuel tank lines and they too were ok. I started it back up and it was doing the same thing again but this time I opened the throttle to full and it died. That said lean lower needle and I wound up opening a full half turn. The engine would now go to full throttle without dying, but still would not respond to lowering the rpm below around 5 K. If I slammed the throttle from wide open to idle it would respond but a normal lowering of the stick had no results. Before this problem came up it would idle all day at 17-1800 and peak a little over 9000K. The answer may be staring me in the face but I am missing it. Any advice would be appreciated.

Change out the throttle servo and see if that changes anything, it maybe telling you something.

Where do you have the throttle servo mounted? Are you on 72Mhz or 2.4 Ghz? Do you have the recommended seperation between ignition and radio components? Hope this helps.

Vbr,

Richard

Sounds like a servo problem.....and could be RF interference

Thanks for the last 3 replies, but I doubt the servo or interference problem. The reason I say that is when I had it on the stand and running after the episode it the air I was looking at the throttle linkage movement and with the engine running the throttle and servo were moving as they should but it did not make any difference in reducing the speed unless I moved it very fast. I have a 2.4 set and a nyrod is used from the servo to the throttle linkage with no metal.

Air leak in intake? Tighten the carb bolts and check the gaskets. Check that the carb insulator is not cracked and leaking. Good luck.

Regards,

Rchard

I would agree with Richard

It very much sounds like an airleak has developed. Take off the plastic insulator and check it for cracks and level. You may need to sand the insulator (put the insulator on the sand paper which is on a flat surface). Then you can use liquid gasket to ensure there are no leaks and re-install and tighten (but not too much).

Cheers
Henry

After reading what everyone posted, it lit my light what Richard and Henry were saying. An airleak has developed. Reading back to my first post where I stated I had to open the low speed needle 1/2 turn to get it to run wide open should have been a bell ringer for me but I missed it. Tomorrow I will pull the motor and carb to find the leak. Sometimes something obvious is overlooked and I appreciate you people helping me.

PM sent

A friend was having similar problems, his engine would not idle down and would not shut off...finally found the butterfly for the throttle was loose. It didn't come off cause it's peaned over so he just added some locktite and tightened it up and problem solved. But it was driving him crazy untill he found it.

Ron