I have posted this issue last week but got only very few replies, tried couple things suggested here but I still have problems.
My Evolution 0.46 engine still doesn't respond to high speed and worst, sometimes it does on the bench but a minute after take off the problem come back, what drived me to land with dead engine twice and break two propelers already.

The problem is shown in the attached picture, showing how the engine responds to the throttle action (values were just supposed).

Here's what I did already trying to fix this issue:
1)Tried to adjust the high speed needle within and out the factory stops, with no results.
2)Checked the fuel tank for air leakage, but found no problem.
3)Contacted the engine customer support. I requested the factory setup for high and low speed needles, just to be sure I would be setting something expected.
4)The customer support said the low speed needle should be aroud 1 turn from the closed position and the high speed needle around 1.5 turns from the closed position.
5)I checked first the range available for the low speed needle based on the factory stops position and it was to lean. I changed the stops to allow the adjust around 1 turn from closed.
6)Tried to adjust the low and high speed needles aroud the position sugested by the factory ( I whent out a bit just to be sure ), got some improvement but far from what I'm sure it should be.
7)Replaced the glow plug to a brand new, just in case.

I just flew solo last Thursday, after the adjusts above, but felt the engine not happy.
Flew again yesterday and the engine started the problem like in the picture again and went dead. Landed hard and broke the propeler for the second time because this problem.

Does anyone could give a light or you guys think I should take this engine to the store and request its replacement? I bought it 2 mo ago.

Thanks,

Nilo

You really need to find someone in your area to help with it in person.

What fuel are you using? Nothing exotic or higher than 15% nitro or lower than 5%? Is the fuel new and not cloudy appearing? What prop? What plug?

Honestly, I think it's still a mixture setting problem. You need to make small adjustments most of the time, the difference between too lean and too rich can be as small as a quarter of a turn with some engines. (though the Evos usually have a broader needle setting).

What procedure did you use to set your high and low speed mixtures? Did you do a lift or pinch test?

On takeoff, it's possible to have an engine lean out and die, even though it seemed OK on the ground. I think that's most likely here. It's also possible for an engine to be too rich and do what you are seeing. There's not quite enough information.

Did the engine smoke? When it's running, do you see liquid fuel spitting from the exhaust? What color is the oil coming out of the exhaust?

While it's possible you have a bad engine, my guess is that it's just not set up correctly. If you can get someone near you to help out, they can actually observe the engine's reaction to various adjustments and tell what is going on.

If all else fails, get a tach. Remove the limiter from the high speed needle, and back it out about 2 turns. Start the engine, and slowly lean the engine, no more than 3 clicks at a time, watching the RPM change. Only change the needle when the RPM has settled to a steady value after the last change, it can take a few seconds for a needle change to take effect. At some point, the RPM will peak, and the next adjustment leaner will result in a lower RPM. That's too lean. You want to be a few clicks on the rich side of that peak. You can also do this by ear if you listen for the RPM change.

Thanks Montague,

Here some more info. I agree that I should get someone to look the engine and see what's going on.

-I'm using 15% fuel, brand new that I bought with all equipment 2 month ago.
-Brand new glow plug, not sure which type it is, but also suggested by the store.
-Prop 10 x 6, like the first suggested by the store.
-I didn't use any procedure for the needdle adjustment but just changing a bit everytime and watching the results. I know I could use the pinch for the high speed (rpm should rise about 300 before engine dies if adjust is correct, right?). I don't have any for the low speed needle adjust. Which one should I use?
-The engine smokes, there is a brown liquid(mostly oil I guess) coming out and also can be seem on the link from the exaust to the fuel tank.

Just to add, sometimes the engine is idle and when you push the throttle like 10%, the engine sounds funny and dies.
I have some experience in car engines but don't seems to be adding anything to this fight!

Thanks,

Nilo

Get some more fuel from a different source it is possible that even though its "new" to you that it sat on the shelf to long

Also Montague's advice is right on follow it to the letter...


BTW 1st rule on engine care is paitence it can take a while to dial some engines in also the engine even though advertised as pre-broken in may not be and might require some running time before it settles down

couple of tips...

Examine all the fuel lines right back to the clunk in the tank. Verify there are no kinks, pin holes, cracks, or leaks of any sort.

Be certain the needle valve's anti rotation spring is firmly seated so that vibration won't cause the needle valve to rotate.

Take out the pin that prevents the needle valve from turning more than one rotation. (The pin is simply press fit, you can pull it out with pliers and put it back in later if you want.) It's a PITA that gets in the way of learning to tune the engine IMO. Don't be worried about getting the needle valve out of wack. Just start with good and rich, and leave the glow ignitor attached while you lean it out - that will keep the engine running if you happened to get it way to rich.

Yes Jim,

I have taken the tank out and double checked the lines for inverted setup and also blown air to the tank and closed all link exits to verify if the positive pressure keeps there and after a minute, the pressure was there.
Likewise, I found the fuel link from the valve to the carb cracked right where it conects to the valve, what was adding bubbles to the fuel to the carb. Replaced but no improvement to the problem that I'm having now.
The needdle has a small plate that press the knob to avoid free rotation, so I'm safe about it.
I have played the valves a lot outside the stops from factory and at some point, I lost the original setup, that's why I requested the customer support for its values.

Next step I'm going to buy a new fuel 15%, another brand. Should I use any specific brand of fuel or glow plug, proved being good?
I heard that there are 4 types of glow plug, indicated for each methanol concentrations. I looked for this value in my fuel but found the Nitro 15% indication, not the Methanol %.Would this "cold" or "hot" glow plug change the engine overall operation much?


Thanks,

Nilo

Althought it's expensive, the OS #8 plug should work fine in that engine with that fuel. You didn't say what brand of fuel you're using though.

If the exhaust is a dark brown it's possible you're running lean and overheating. Though with out knowing the brand of fuel, I can't tell for sure. (and assuming it's a brand I'm familar with).

I think a 10x6 is a bit small for that engine (depending on the brand of prop). Combined with a lean run, it could lead to overheating and performace very much like you describe. (I once had overheating problems due to a bad cowling job, and the engine would die in a way that was simular to what you describe).

Try a slightly bigger prop, say a 10x7 or 11x5 or 11x6. I happen to like APC for a brand. If you're using the black Master Airscrew props, they do tend to load the engine less, resulting in higher RPM

However, I honestly think your biggest problem is still a lean run.

Try starting really rich, like Jim and I said. You should hear the engine "4-cycleing" at full throttle. That is, the exhaust note sounds noticeably different, as if the engine is missing every other stroke (which, in fact, it is). Then slowly move in the needle valve. You should hear the engine "break" from 4-stroke to 2-stroke. Usually you get a few clicks where the engine kind of wavers back and forth, then a couple more clicks lean and the sound turns in to a "clean" 2-stroke whine.

If you are just learning to fly, you can take off with the engine just barely out of 4-stroke, and you'll still have plenty of power.

If you've never heard the difference between 2- and 4- stroke operatoin, you've never been rich enough. Back out the needle more.

It's possible (though I haven't seen anything to tell me for sure) that you have some dirt or debris inside the carb that is causing lean runs regardless of the needle setting. Not likely, but possible.

Thanks guys.

I have some to go back to the work bench and try some more.

I will let you guys know how it goes.

Nilo

Montague's advice is great (as usual!). Follow it. It really does sound as though you're running a little too lean. It may be fine on the ground, but once in the air, the prop unloads a little and the engine leans out some more. Either use the "pinch" test, or hold the nose of the plane up at least 45 degrees at full throttle. You should also hear the rpm increase, then decrease again as you lower the nose to level.

You should also be fine with an OS A-3 glow plug if you can't find a #8 (best), and Montague's prop recommendations are right on too.
Dennis-

I don't know half of what these other guys do but I had a similar problem. It would run great on the bench, take off and die. There was also intermittant problems with transition. It turned out that I had an air leak around the bottom seal where the carb plugs into the engine. You also might check around the barrel of the carb for bubbles. Just a thought, but it's part of what my problem was.
Rick

Rick,
Good point, and certainly worth checking.

The Evo comes out of the box with the carb already mounted, but it's quite possible it was factory mounted not-quite snug enough.

I've had some engines that leak air around the needle valve (poor quality o-rings). Those get cured with a bit of fuel tubing around the needle. I don't think he's leaking air around the needle (engine is too new), but who knows for sure.

Good feedback.
I will check the carb. The fuel link from the valve to the carb was bad before, creating bubbles, but I replaced and I don't see any bubbles anymore inside this link, so I suppose the valve seal is good.

Thanks,

Nilo