Hi,

I know there have been several threads on tuning this engine but I didn't find the answer. I've got a new Evo .46 engine that worked beautifully for several flights and then started to have stalling problems. I've messed around with the high and low tuning screws extensively but can't seem to find a spot where it transitions well and also will run for more than 10 seconds without stalling.

Here are the symptoms;

When the engine starts it will run fine from mid-throttle back to idle but if it's opened wide it will run fine for about 5 to 10 seconds and then slightly increase in rpm, then bog out to an idle, then rev up to full rpm, then die. This sounds to me like air is getting in somewhere. I've replaced the O-ring that sits against the bottom of the carb since some people mentioned air leaks but that didn't seem to help.

The manual does not state the factory settings for the low and high screws, does anyone know how many turns these are supposed to be set at? Anyone have any other suggestions?

Thanks,

Mike

Concentrate on the top end first, get some time on the engine. It sounds
like it is running too lean. Can you get the restrictor off the high speed
needle ? Get it running to peak RPM, then open the needle till the engine
slows down a bit....that is a rich condition. Run it like that for 10 minutes,
then shut it off and let it cool. Refill the tank and run it again for 10 minutes.

Now you should be able to get some good settings on the engine.

FBD.

Mike,

I have the EVO trainer and I’m having a very similar problem as you are having. I had a couple of good flights then it started acting as you described. It will idle ok but when I go to full throttle it runs ok for a few seconds then starts to bog down to almost an idle then it might speed back up then down again. I too tried resetting the high and low idle adjustments but could not find a spot where it ran ok. I never had a problem getting it to idle but just could not keep the RPM’s at full throttle. I did notice that I was getting a lot of black stuff coming from the muffler into the fuel tank. I removed the baffle from the muffler and tried a fresh tank of fuel. No more black stuff going into the tank and it would run ok static. I ran 2 tanks of fuel with no problems. It has been to cold and windy here to take it back to the field to see if it does ok in the air. I did the pinch test with it running at full throttle and also held the nose of the plane up 90 degrees and it ran ok. I don’t think one should have to remove the baffle to get this engine to run but that is what worked for me. I would send it in for repair but I can’t find my receipt.

Mike

Funny how I am having the same problem with the EVO 61 engine!! Ran not bad for a few flights and then it seemed I had to run it really rich just to keep it running in the air. Problem is, at this setting the prop is only turning around 10.5 k instead of the 12k as advertised. I never did get 12k out of it. The best run was around 11.3k. Pulled the engine and replaced it with a TH 75 engine which has tons more power and not too hard to adjust.

Having the same problem with my Evo .40 trainer...tried taking the baffle out, but that made the problem worse. Finally I just said the hell with it, reset the h/s needle to factory (2 to 2 1/2 turns out), and actually closed the h/s needle to about 1 3/4 turns out. It ran well at this setting.

For a supposedly "hassle-free, great engine for beginners", this engine sure has turned out to be a POS.

I think a lot of people make the mistake of thinking that "hassle-free" means "no adjustment." Any model engine of any brand is going to require adjustment from day to day, and even sometimes from flight to flight on the same day. Atmospheric conditions (temperature, air density, humidity, etc.) will affect how the engine runs. In many cases, as theengine heats up after a flight or two, it may require some additional tweaking to keep it running right. Also, some of the problems you guys are describing sound like a possible air leak somewhere int he system (carb? fuel line? muffler?). The most insidious one i've experienced, which baffled me for some time because the engine was cowled, was a razor thin cut in the fuel feed line right at the copper tube coming out of the tank. I thought the fuel leak I was seeing coming out of the cowl was from the muffler coupling being loose so I kept trying to tighten it, but never noticed the cut fuel line until the engine quit on me on short final. The leaking fuel had weakened the wood at the landing gear mount, and....*poof*....off came the gear on a fairly normal landing. Fixed both the fuel leak and the gear and she's now flying again. By the way...this is an Evo 46NT I'm talking about. Also have a .455 trainer engine I'm waiting to put into another plane soon. I like the Evo's so far (and yes, i removed the h/s restrictor right away!). Good luck with yours!

Ahhh yes, but an extremely powerful, high rpm engine once you find the magic combination on the needles.

what was ambeint tem. when runing engines.

If you live in the north east your engines mite be to cool to maintain opr.tem

dave. i fly in cold temp and i us strip of foil to maitain op. tem

Yes, once the right settings are found, I'm sure the engine will be fine. But the manufacturer shouldn't mislead people into thinking that the engine will run great right out of the box.

And while it's true that I am a newcomer to this hobby, this engine of mine has baffled even the most experienced guys at the club.

Hi!
The way you describe it ...you simply run the engine too lean!
Open the high speed needle and try again!
Regards!
Jan K
Sweden