RE: I hate my evolution .61
 

If it is a tank issue changing engines will not help.
Do you see air bubbles in the fuel line when holding the nose up while the engine is running?

RE: I hate my evolution .61
 

Not necessarily.

Since you are talking about the engine quitting when the plane is going straight up, the engine is leaning out more, the lower the fuel gets.

That's because the carb must generate a lower pressure area to get the weight of the fuel up the effectively increasing in length line.

If the muffler is not creating enough pressure in the tank, and/or there is a leak somewhere before or in the carb area, the low pressure seen at the carb may not be enough to pull the fuel up, starving the engine causing it to quit.

I hope you tuned your engine with about 1/3 of a tank of fuel in it, but not much more...

Then once you got it tuned you performed a nose up test to check your settings.

Did you skip this by chance?

RE: I hate my evolution .61
 

Normally I just fill the tank and tune,but for this plane we also tested it at maybe half tank. Most of us at the field are very strict about holding the nose up at full throttle before the first flight of the day. My Sukhoi with this .61 EVO in it usually seems to be OK on the ground with its nose up,but in the air is when it gets iffy. I never really checked for air bubbles. I do notice however this is common on alot of planes I see people tuning etc. and they run great. Heck,thats how you can tell the fuel is flowing,lol. I actually havent been testing it too much lately as I've just gotten used to it and know when not to push it. This thread kinda got more into then I had expected. I just wanted to say how I didnt like my EVO. I'm kinda glad it did now though,because I'm starting to want to play with it more to figure it out,lol. This weekend when I go to the field I'm putting it through the ropes! I might even take the tank apart before hand just to put in new fuel line and double check things again,then see how she does. I also want to test and tune it with about 1/3 tank of fuel as opjose mentioned.

Tell you guys what though,if I test it and it dead-sticks me again and I finally crash it, I'm blaming it on you guys!!!!!!!!!!

:)

RE: I hate my evolution .61
 

I'm a beginner but heres my $.02 .
Run the engine at half throttle with the plane level. Slowly tip the nose up vertical and listen for any change. just to see verify if its leaning out.
I don't know much about the plane you got but try sticking a 4 oz. tank in it and making a couple of quick flights. The amount of space your pressure line has to fill will be different. If you get any change with this youll know it not the motor ..if ya don't ya know it is.
That just a quick test for the fuel supply system.

Good luck

RE: I hate my evolution .61
 

I will offer my humble opinion if I may... I have 6 Evo's... 2 .46, 2 .61, and 2 100's. I had no problems with the .46's, they are more powerful than my O.S. .46 FX, which runs well too. I expected the same out of the .61 & 100, but I had the same problems you are having, i.e. inconsistant carb settings, lean outs, floods, dead sticks... it seemed like every different attitude my plane was in would bring on a different symtom. I was so sick of the 100... I tried EVERYTHING TO GET IT TO RUN RIGHT. I worked on that thing for months it seems. I even bought a new one and tried it, & it had the same problems. Then I got a wild idea. I would try adding a little restriction to the muffler. It just might be crazy enough to work!

So now I offer you a simple solution that has me jumping for joy again... try increasing the muffler back pressure slightly. While at full throttle, I did this by CAREFULLY (remember the prop!) squeezing the exhaust pipe with pliers just until the engine starts to decrease rpm, then I opened the crimp back up with a flat blade screwdriver JUST until it had full song back & then reset the high and low. IT WORKED LIKE A CHARM!!! I couldn't believe the difference! Now the .61's and the 100's are dead reliable, and powerful! Especially the 100, (also mounted inverted) which I thought was doomed to the sledgehammer for sure. you could also try putting a silicone muffler extention on the exhast and crimping it down a little with a zip tie if you are worried about taking pliers to your muffler. Easilt reversible and cheap. Don't give up on this engine as I almost did. While the root cause of this problem may not be muffler design, the CONSISTANT fuel draw problem with these larger EVO's can be cured with no loss of power with this method if done properly. Try it and let us know how it worked- I sure am smiling again.

P.s. This isn't Evoution public relations, just me showing you how I got the most out of my substantial investment. Still, I don't really know how they missed this in the "factory" break in and adjustments!