I'm having problems getting my Evolution to run for more than 5-10 seconds at max throttle before dying from what seems like lack of fuel. It starts and runs consistently at up to half throttle, but once I throttle up it simply dies regardless of the setting of the high speed needle valve. Yes, I have also tried opening the needle beyond the initial factory setting.
At first this made me think of a fuel tank problem, but I've changed the fuel tank, tubing, and filters without seeing changes in the engine's behavior. Also I've tried two other engines in the plane using the same tank, filter and tubing without having any problems whatsoever, so I'm left with the engine. (I even tried placing the tank on top of the fuselage to ensure that the tank level is above the carburetor).
I've complained to my local store where I bought the engine, and they supplied me with different fuels, plugs, and even a spare needle valve assembly. All have been tried with no changes to the engine's behavior. As a final solution the store changed in my first buy and I now have a second Evolution .46 that I tried out for the first time today. Guess what - the engine behaves in exactly the same way.
I'm operating in Oslo, Norway. Temperatures when trying the engines have been around zero degrees Celsius/32 degrees Fahrenheit. I haven't heard of temperature related problems earlier, but maybe others have.
To me, this seems to be related to the engines ability to suck fuel into the carburetor, or the mufflers ability to pressurize the tank. There seems to be a vacuum effect that "pulls" the fuel back into the tank leaving the engine with too little. Why this happens only with the Evolution and no other engine I've tried in this plane I cannot understand!
This has become very frustrating - the Evolution is supposed to be one of the easiest engines to operate and I haven't been bothered to take mine to the airfield once after owning one for several weeks. Any help is extremely appreciated.

Hoping for miracles
Henning

we have had those exact problems just today after my son and i put the engine in a ucd 46 and prior to that it was in a h9 arrow with no problems. so we finally figured that this engine does not like to run inverted. we turned the engine over and it is now running fine. you never stated weather or not your engine was inverted or not , please let us know.


Thanks

The engine is not inverted.

I spent several hours trying to fight the same symptoms on one of these engines, in the end we swopped the silencer for one from an OS46 and no more problems!

I had the same problem with my EVO .46 also. I removed the baffle from inside the muffler and now it works just fine. You might give that a try. It looked like fuel/oil was pooling up inside the muffler and was not getting past the baffle causing the engine to choke.

Mike

there is a small notch on the edge of the baffle and i believe that this notch is supposed to point down for that reason Mike. i dont know if it was intended but it works because i noticed the same prob. ive had this engine for over a year and always fought it for transition but the first thing to do is grind off that little notch and tune it by ear and tach, not using the stops.

Mine was pointed down because I took a look before taking it out. I wonder if I would use fuel with less oil if it would work better with the baffle in. Anyway works fine with it out. Just got back from our local flying field with two good flights.

Mike

You guys were absolutely right! I just got in after running one full tank at full throttle. I took the baffle out before trying. Guess I'll try to take a closer look at the baffle another day to see if I can put it back in and still have the engine running fine and with better noise reduction. I'm curious as to why my hobby shop didn't suggest this before giving me a new engine to try out. They too will be wiser tomorrow.

Thanks again!

By the way did any of you do any special breaking in of your EVO's? Would you recommend breaking it in or skip it and make it scream from first flight?

Hi!
Hej!
All engines benefit from a break-in...as yours is ABN or ABC engine just running it slightly rich the first (3-5) couple of tanks is enough and running-in could be done in the air.

Regards!
Jan K
Sweden

Just curios if your problem is solved via the muffler ducting? I just purchased the same engine and have been fighting this problem since about the third flight. When i do bench runs, it seems that there is air getting into the intake tubing after the needle fitting!?
If what you did worked for you then I will try that. thanks
bp

Yes, my problem is solved by having modified the baffle (the plate inside the muffler that looks like a Swiss cheese). I have cut away about 5mm at the top and bottom of the baffle so the exhaust flows more freely out of the muffler. I first tried to bend open the small openings in the baffle. This made the engine run a bit longer before choking, but I either had to remove the baffle all together or cut away bits of it before it would run consistently

There is of course the possibility that your problem is related to air getting into the tubing between the needle and the carb. Try changing this tubing first, if the problem persists then remove the baffle (or the other way around).

Good Luck
Henning

I removed the baffle completely and still same problem am looking at re sealing the intake needle and then playing with the idle and high speed needle.
thanks again
bp

Hi!
It's hardly the baffle that is the problem! Can't believe the factory didn't do a lot of testing before starting manufacturing.

Regards!
Jan K
Sweden

I have both the .45 and .46NT Evolution engines and they are both great. Both also had small air leaks in the fuel tubing from the HS needle valve to the carb. I changed that right away. On my .46, I took the baffle out before I did anything else.

I've read and heard about problems with the settings done in China for the needle valve settings. A lot of people need to reset theirs to their own location. I took the collar off of my engines.

These engines are manufactured to be tight. I ran mine for a few minutes before flying. It had more power than my OS .46FX on the first full throttle takeoff, but it didn't really run smoothly for another 5-6 tanks of fuel. It now sips fuel almost as good as a my 4 strokes.

I disagree with the assertion that these engines weren't tested properly. They are some of the best 2 strokes out there. They are very forgiving if you don't have the needle valves set properly. They rarely, if ever, give you dead sticks. The crankcases don't seem to load up much. You just have a problem somewhere and it happens all the time.

How far back is your fuel tank? Is is lower than the engine? Can you run the engine and see if the vent line system is working properly? Is your vent line in the tank unclogged? Are you sure you have the needle valves really set properly? What prop are you using? What is your nitro content? What plug are you using? Maybe it's time to checx all of these things. And, maybe the HS needle valve needs back flushing.

Hey thanks for all your input, today after work I built a small test stand and put the engine in the Test Cell, so to speak.
What I found is a small crack in the fuel line between the needle and the carb...so with a little safety wire and a new fuel line, I am no longer AOG...or EOG...
I agree that this is a well built motor and am sure I need to finish breaking it in,am looking forward to re-installing the engine and seeing how it can perform.
thanks again
bp

I wonder if thats why my Evo 61 runs like crap?!? I'm taking the baffle out to find out! [>:]

You should find this to be a good engine. The Tower Muffler gave mine around 1000 more RPM and was worth $17. I use Omega 15%. You may want to try the APC 12.25x3.75 prop on the UCD. It should make a very big difference.

Don't forget to change out the glow plug you are using to break it in some more. When you think it is getting smoother go ahead and put a new OS 8 in it.

ok I am back to square 1, replaced the fuel line and thought we had it solved but now once it gets hot, it will not run for more then a min or two..."great"/
the other oddity is I have developed some sort of leak, seems to be the muffler gasket but cannot be sure as of now. was curios of anyone basic needle settings, I am starting at three full turns open ....I am in central valley ca, usa...about 100 feet above msl.\
Well at least it is the weekend and I can spend the time trying to resolve the problem,
thanks again
bp

I am glad I found this thread, I was about throw this engine (Evolution .46) away. with a full 6 oz tank, I had 8 dead sticks once the engine got hot. Just because I didn't care any more what happened to this engine, I put some Magnum 30 % heli fuel in it, and boy, the sucker runs like a champ. Idle forever, runs great all the way through. and when it landed it was nice and cool.
But I will try taking the baffle out of it tomorrow, and go back to the cool power 15% and see what that does. If not, I will run the Magnum 30% heli fuel in it (lots of power)