Evo 60 Test Report
Just thought I would share this “data”. (Data means that I do not necessarily understand nor can explain it) but if you are considering an Evo 60, it is good information.

In my first experience with an Evo 60, I put it into a Shark 45 and had engine runaway/lean out problems once it was airborne. I finally “solved” it, or appeared to, when I isolated the tank with Styrofoam sheets. I now get good and consistent engine runs. So, I bought a new Evo 60 for a Legacy I was working on. I always put at least one hour bench time during the engine break-in process and here are observations during the break-in.

First half hour with no muffler. All seemed as it should.

Second half hour: Put on the tube muffler and the engine settled in at about 7900. If I “needled” up, it tended to “lean out” and run away to about 9000. Adjusting the needle down did not find a happy spot. It had a tendency to lean out, or if I leaned it out by squeezing the fuel line, it did not want to come back down to a lower 4 cycle.  I pulled the tank off the test stand and held it in my hand, thus isolating it from the vibration, to see if that cured the run issue. That did NOT help noticeably. The engine wanted to run at 7800 to 7900 RPM or lean out to a higher and not controlled RPM.

I then put on the tongue muffler and that seemed to help a lot. It did not have as much of a tendency to lean out. I could adjust it to 8200 RPM and have it be consistent. 8200 is my target RPM where I want it to run reliably. For my Shark, that RPM with a Xoar 12x6 is a good combination.

I put the stock small venture on. Small venturi with the tongue muffler was best. Ran well, stayed where I adjusted it and came back to that RPM if I pinched the fuel tubing to lean it out momentarily. By the way, most people on the forums recommend the small venturi. I run the small one in my Shark as well.

I put the tube muffler back on and it was better than before although it was a little slow dropping the RPM back to my set point when I pinched the fuel tube.

Bear in mind the engine is getting more run time as I was doing these changes so I do not know how much was break-in related and/or muffler/venturi related. I was not running muffler pressure since most people on the forums do not recommend it and when I tried it early on, it did not seem work as well for me. Admittedly, I have not tried it since the engine is running well, but then if it is running well, why “fix it”.  In any event, I put the new Evo on the completed, albeit heavy, Legacy.  (74 oz.)

At this point, I flew both the Shark and Legacy for a few months.  When I flew both those planes at the Regional contest in Eugene, OR, I had several people ask what engine I was running.  That was because of the great engine runs I was getting (and not because of any great flying skills that I was demonstrating).
Now that the hot weather hit, I have had to make some adjustments.  Turns out these adjustments worked in cooler weather as well so no need to keep changing things.
I found that in a hot and strong wind, I had to run at about 8500 RPM to get a good flight with sufficient line tension.  Since the motor really likes 8200 to 8400 RPM, the 8500+ to get the good speed gave me less than a desirable engine run.  The engine really likes 8200 to about 8400 RPM. The other thing that happened was that in the heavy wind, the engine would lean out going into the wind and sometimes would not drop back down.  That caused a significant increase in speed, which was too much for me.
First I tried muffler pressure once again.  That fixed the tendency to lean out when going into a strong wind.  I now have more than 25 flights with muffler pressure, both windy and not.  That is giving me a good steady engine run.
The other thing I did that also contributed to settling the engine down in hot, windy weather was to change the prop to a Xoar 13 x 6.  I am now back to about 8300 RPM and running about 5.1 lap speeds.  The only drawback to the larger prop is “lawn mowing” and higher RPM.  If I get the RPM a little high, say closer to 8400+, the plane pulls like a truck and there are times it is hard for me to keep my “stance” (because of the strong pull) in some of the maneuvers.  At about 8300 RPM, however, all is good! 
I share this because the Evo’s in both my planes give me good reliable engine runs.  They are relatively inexpensive motors and generally sales priced around $140, so a good bargain for a larger engine.  They come with two venturi’s, a tube muffler and a tongue muffler.
My current set up is as follows:
Xoar 13 x 6
Muffler pressure
            One head shim
            Cool Power 10 nitro and 17 synthetic
            Launch about 8330 on a 74 oz. Legacy
             Fox Miracle Plug

(Ok Evo, send me a free 60 for this good review!)

I certainly agree with you.  When you put the brass tube on the stock muffler, how long did you make it?  I don't recall off the top of my head how long the stinger on the stock pipe is.  But I would assume you made the new "stinger" shorter?

Tx.

Mike

I just use a Big Art tube muffler.

I also have a heavy Legacy (71 oz) with an Evolution 60 and I tried a number of things over a year to get a good stunt run, but I eventually gave up and hung it on the wall.  After reading this thread I removed all the head shims I had previously added, put on a Zoar 13 x 6 prop, used 10% fuel with low oil content and launched at about 8200 RPM.  Bingo!  Although not perfect, it pulled it through the pattern without dislocating my shoulder.  I am glad I didn't step on the plane in frustration,  and I really like the way it flies with a strong steady pull on 65 foot lines and 5.4 to 5.6 second laps.  Thanks for the tips guys!!!!!

Don

The instructions do state you should use Cool Power Omega or Power Master fuels containing 5 to 10% Nitro.  Early on, I tried Sig 10 Nitro with 20 lubricant, half synthetic and half castor.  Did not get good engine runs at all.  I then added 2% additional castor.  The engine liked that even less.  It would quit after about a half a lap.  I use Cool Power 10% and 17% synthetic.  It runs great on that.

Just moving this up for Andrews information.