very rough running 912uls

[Slyfox]

20221122_081503.jpgIt's time to share what happened to me last saturday when I went for a flight in my kitfox. This airplane has the 912uls. Over the summer I've had multiple problems, one of them was carburation. I ended up putting a used carb on the 1-3 cylinder side. It has been flying flawlessly now for a couple months. Well saturday I took off and flew south east and was going to fly a low approach over an airfield about 5 miles south of felts field. I went and pulled the throttle and as soon as I did the engine started running real bad, like I had lost a cylinder. I put it to full power and was able to limp it to the runway and land without any trouble. powered up to get off the runway and it would pull itself. felt very fortunate. I had to borrow a friends trailer and haul it back to the airport. I then went and pulled the spark plugs and found no. 1 plug was white as can be, all other nice and tan. I pulled over the prop and all cylinder were equal. I than pulled the valve covers off the two right cylinders and found all valve stroking equally. I felt it was running super lean, so I removed the carburator for 1-3 and this morning pulled off the top, what I found was the main jet needle had broken at the clip. the needle was jammed down in the jet. So rebuild of this carb and all should be good again. I have heard if the clip wears into the needle this can happen. take care