I'm having some problems with my Evolution 58. The engine was run for the first time since it came back from Horizon for repair. The engine checked out and the necessary parts were replaced. The first problem started to occur yesterday, but we just thought maybe it was because the engine is so new. I'd take off with the needles set just about perfect and then toward the end of a 12 minute flight, the high end would get a little richer. This was confirmed by flying along at full throttle and then engine would burble, but clean out if I pulled into a 45 degree or straight up vertical attitude.

Then, when I was going to make the last flight today, I had trouble getting the engine to start. I thought maybe I flooded it. However, when it ran, I could only get full throttle by slowly advancing the stick. I thought maybe it was a little lean, but richened the low end eventually as much as a 1/4 turn with the same result. The engine also appeared to be lean as smoke was coming from the muffler as if it was too hot. It was also making a slight whining noise when idling and I was constantly changing the idle setting as it was idling faster than before.

I pulled the engine and checked all of the bolts and screws to try to find a loose one that could be causing an air leak, but found nothing. I opened up the carb to see if the screen was clogged and it was clean. I'm all out of ideas.