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.

First I'm sorry to hear that you are again having problems [:'(]. I'm sure someone will give you better info than me but I'll stick my neck out anyway because it's a challange to learn.
1. I would contact Horizon or some competant dealer or the factory.
2. At first I thought that perhaps your ignition module might be going bad on you. You had said that it was at the end of the flights which would give it time to heat up and malfunction possibly changing your timing or providing a weak spark which to me "might" contribute to the burbling and the changing of the idle and even possibly heating up and at the last part was hard starting. The only thing is I don't see how the module would whine.
3. The whining means to me that if you have a "rotary valve" it is dragging or the bearings on the front are heating up and giving you problems. I'm probably wrong but with limited info I would be checking out the spark and then the binding.
4. I don't see how the carb could be changing settings on it's own that much unless possibly the diaphram for the pump has a very small hole in it or a needle or something is not seated properly and it's not pumping the fuel to the engine constantly. My thoughts on that though are "it would work or not work period".
Okay everybody come on out and show me how wrong I am - I can take it...........Bill

Hey Ben, I was just thinking about that whining noise you mentioned. If the engine is not dragging could it be a whine or whistle do to something sucking air through the diaphram or some valve vibrating in the carb itself.??? Maybe spray some oil around the carb etc. and flip to see if it's sucking air or disassemble???. Bill

Well, like I said, I inspected it. I decided late last night to just send it in....again. I called Horizon to and explained my dissatisfaction with the engine. I explained all of the problems to them and once again made known what gas and oil I was using. They shouldn't need to replace a crank this time so hopefully I have it back sometime next week. This is getting old though.

Oh, the burbing at full throttle would go away if I pulled up into a 45 or straight up verticle climb. Just something to cause the engine to lean out enough. I rotated the engine and everything sounded smoothe so I don't know. I didn't want to disassemble the carb too much either.

My CF spinner also is not longer usuable, could that make a whining noise? I've dropped about $250 into problems with the airplane as of yesterday. I was out at the field and my choke servo went bad because I used one with karbonite gears (didn't know they were that sensitive) so I replaced it with the throttle since it was the same model servo and put a mini digital with metal gears on the throttle. I ordered a second mini digital with metal gears since the LHS didn't have two of them from Tower last night. I also ordered a spinner from Tru Turn. About to order a new prop since I was using a Mejzlik and I want to reduce the weight a little bit on the nose.

It should prove interesting to see what they claim went wrong this time. I don't blame you for not wanting to take anything apart. Please keep us informed.....Bill

Ben did you ever figure out the problem with loosing RPM's in a waterfall? I ask because I lost my plane yesterday due to this problem that was the first time it ever gave me any trouble and it definitely wasn't the first waterfall that day either. the engine bogged down on me when it was coming over the top of the waterfall and since I was pretty low to begin with it went splat. right before it hit the rpm's started to recover just enough to keep it from going in lawn dart style. sound at all familiar?

I added an intake trumpet and then we ran a piece of fuel tubing from the other breathing nipple on the carb back into the fuse. We got the RPM's, but then lost them when the engine richend up. One thing is for sure though, If I have to send it in a third time, I 'll do it but it's getting sold when it comes back and i'm getting a 3W 56.

Need Help please on my evolution 58cc

idle and high speed is perfect on floor but after 5 minutes on air, the 58cc cut out at high speed..
sorry for my english...